Abstract

Weight cycling has been associated with an increased risk of death in some studies, but few studies differentiated weight cycling initiated by intentional weight loss from that initiated by illness. The association of weight cycling with death was examined among 55,983 men and 66,655 women in the Cancer Prevention Study II Nutrition Cohort from 1992 to 2008. A weight cycle was defined as an intentional loss of 10 or more pounds (≥4.5 kg) followed by regain of that weight, and the lifetime number of weight cycles was reported on a questionnaire administered at enrollment in 1992. A total of 15,138 men and 10,087 women died during follow-up, which ended in 2008. Hazard ratios and 95% confidence intervals were estimated using Cox proportional hazards regression models. When the models were adjusted for age only, weight cycling was positively associated with mortality (P for trend < 0.0001). However, after adjustment for body mass index and other risk factors, low numbers of weight cycles (1–4 cycles) were associated with slightly lower mortality rates (hazard ratio (HR) = 0.93, 95% confidence interval (CI): 0.89, 0.97 in men and HR = 0.93, 95% CI: 0.89, 0.98 in women), whereas high numbers of weight cycles (≥20 cycles) were not associated with mortality (HR = 1.03, 95% CI: 0.89, 1.19 in men and HR = 0.99, 95% CI: 0.88, 1.12 in women). These results do not support an increased risk of mortality associated with weight cycling.

Obesity is a serious public health problem in the United States and elsewhere. Approximately two-thirds of American adults have high body mass indexes (weight (kg)/height (m)2; BMI) and are classified as overweight (BMI of 25–29.9) or obese (BMI ≥30) (1). A high percentage of US adults (55% of women and 39% of men) are currently trying to lose weight (2). However, most people who lose weight later regain it (3). Repeated cycles of weight loss and regain are referred to as weight cycling. The prevalence of weight cycling, for which there is no standardized definition, has been reported to be approximately 18%–34% in men (4, 5) and 20%–55% in women (4, 6).

Because of the high prevalence of weight cycling, it is important to understand whether it results in adverse health consequences. Some of the potentially adverse effects of weight cycling that might influence mortality rates include possible redistribution of body fat from peripheral to central locations and slowing of the basal metabolic rate, which would make future weight loss harder; however, the scientific evidence supporting these effects is minimal (7). In several studies, investigators reported that weight cycling is associated with an increased risk of all-cause mortality (8–13), whereas others found no association (14–17). All except one study (16) defined weight cycling based on patterns of body weight either measured by study investigators or self-reported at different points of time without taking into account whether the weight loss was intentional. In contrast, in the study by Field et al. (16) in which investigators found no association, history of weight cycling was based on self-reported intentional weight loss of specified amounts. It is critical to differentiate between intentional and unintentional weight loss because unintentional weight loss is often due to comorbid conditions that in turn may be strongly associated with later death. Others examined the associations between weight cycling and the risk of conditions that might influence mortality, including myocardial infarction (18), hypertension (19, 20), stroke (18), diabetes (18, 21), bone fractures (18, 22), gallstones (5), and various cancers (23–25). In these studies, different criteria to define weight cycling were used, and the results often conflicted.

Understanding the effects of weight cycling has important public health implications. Over half of the US population is overweight or obese, and most weight loss is not maintained. Therefore, the prevalence of weight cycling is likely to increase. If weight cycling does increase risk of death, greater emphasis should be placed on prevention of weight gain and maintenance of weight loss.

To specifically address the question of whether weight cycling resulting from repeated periods of intentional weight loss followed by regain is associated with increased mortality rates, we conducted analyses using the large American Cancer Society Cohort, the Cancer Prevention Study II (CPS-II) Nutrition Cohort from 1992 to 2008. Analyses were adjusted for measures of weight history to determine the association between weight cycling and mortality independent of these factors.

MATERIALS AND METHODS

Study population

Subjects for this study (86,402 men and 97,786 women) were participants in the Nutrition Cohort of the CPS-II. The Nutrition Cohort, which has been described in detail elsewhere (26), was initiated in 1992 as a subgroup of the CPS-II, a prospective study of cancer mortality involving approximately 1.2 million Americans that was begun by the American Cancer Society in 1982. Participants in the Nutrition Cohort were recruited from a pool of CPS-II members who resided in 21 states and were between 50 and 74 years of age. At enrollment in 1992/1993, participants completed a self-administered questionnaire that included questions about demographic, anthropometric, medical, and lifestyle information. Usual dietary intake over the past year was assessed using a 68-item food frequency questionnaire developed by Block (27, 28). All aspects of the CPS-II Nutrition Cohort study were approved by the Emory University Institutional Review Board (Atlanta, Georgia).

Deaths were ascertained by biennial automated linkage to the National Death Index (29). Multiple cause-of-death codes were obtained for 99.3% of known deaths in CPS-II. Follow-up ended at the date of death or December 31, 2008, whichever came first.

Exclusion criteria for this analysis were as follows: report of prevalent cancer in 1992 (10,129 men and 13,501 women); a history of heart attack, stroke, emphysema, or other lung disease in 1992 (14,777 men and 8,338 women); missing information on BMI in 1982 or 1992 or a BMI <18.5 or >50 (1,726 men and 3,917 women); missing information on the number of times a participant purposely lost 10 pounds or more or the number of times a participant regained weight that was purposefully lost (926 men and 1,774 women); a report of never having purposefully lost 10 pounds or of 10 or more pounds being the most weight ever purposefully lost (908 men and 871 women); and report of a number of times that weight was purposely lost that differed from the number of times weight was regained by more than 2 (1,953 men and 2,730 women). After these exclusions, a final cohort of 55,983 men and 66,655 women were available for this analysis.

Identification of participants who experienced weight cycling

We determined whether individual CPS-II Nutrition Cohort participants experienced weight cycling based on their responses to 2 questions about intentional weight loss and regain on the 1992 baseline questionnaire. The first question asked, “How many times in your life have you purposefully lost 10 pounds or more?” The second question asked, “How many time in your life have you regained as much as 10 pounds that you previously had lost?” A write-in answer was required, with spaces for 2 digits provided. Thus, answers could range from 0 to 99. A weight cycle included both a purposeful loss and a regain, and cohort participants were classified by the number of weight cycles they reported. These criteria resulted in the identification of 32,451 men and 28,823 women who had not experienced weight cycling (hereafter referred to as noncyclers) and 23,532 men and 37,832 women who had (hereafter referred to as weight cyclers). The total number of weight cycles reported was used to further classify the weight cyclers into 4 groups of 1–4, 5–9, 10–19, and 20 or more weight cycles.

Statistical analyses

BMIs of participants in 1982 and 1992 were calculated using weights reported at each of those times, whereas BMIs at 18 years of age were calculated using recalled weights reported in 1992. Weight change between age 18 years of age and 1982 was calculated as the difference between the recalled weight at age 18 years and the reported weight in 1982. Weight change between 1982 and 1992 was calculated using the weights reported at each of these times. The validity of recalled weights at either 18 years of age by middle-aged adults (30) or at 20 years of age by elderly subjects (31) has been shown to be very good.

We used Cox proportional hazards regression analysis (32) to calculate hazard ratios and corresponding 95% confidence intervals for the association between weight cycling and mortality. P values for linear trend were estimated by modeling the number of weight cycles as a categorical variable, with the median value determined for each category. The Cox proportional hazards assumption was tested by modeling multiplicative interaction terms between weight cycling categories and time. The statistical significance of the interaction terms was assessed using the likelihood ratio test (33). No violation of the proportional hazards assumption was found.

All Cox models were stratified on the exact year of age of the CPS-II Nutrition Cohort participants in 1992. Additional covariates included in the multivariate-adjusted models were race (white, black, or other/missing); alcohol consumption (0, <1 drink/week, 1–6 drinks/week, 1 drink/day, ≥2 drinks/day, or missing); current smoking status (never, former, current, ever, or missing); for current smokers, number of cigarettes smoked per day (≤10, 11–20, 21–30, or >30); for former smokers, combinations of years since quitting (<9, 10–19, or ≥20) and number of cigarettes formerly smoked per day (≤20 or >20); educational level (some high school, high school graduate, some college, college graduate, or missing); BMI in 1982 (18.5–22.4, 22.5–24.9, 25–27.4, 27.5–29.9, 30–34.9, 35–50, or missing); weight change from 18 years of age to 1982 (lost >5 pounds, lost 5 pounds to gained 5 pounds, gained 5.1–20 pounds, gained 20.1–40 pounds, gained 40.1–60 pounds, gained >60 pounds, or missing); history of high blood pressure (yes or no); history of diabetes (yes or no); total energy intake in gender-specific quintiles; and physical activity in metabolic equivalents (0, 0.1–6.9, 7–17.4, 17.5–24.4, 24.5–31.4, ≥31.5 hour/week, or missing). Physical activity was assessed on the 1992 enrollment questionnaire by asking about the average time per week during the past year spent performing any of several activities. Summary metabolic equivalent hours/week were calculated by multiplying the lowest number of hours in the response by the metabolic equivalent score for each activity according to the Compendium of Physical Activities (34) to provide conservatively estimated summary measures. Usual energy intake was estimated at baseline from individual responses the 68-item Block food frequency questionnaire. Energy intake from each food was estimated using the Diet Analysis System, version 3.8a (28); usual energy contributions from all individual foods were summed to provide overall average intakes.

BMI in 1982 rather than BMI in 1992 was included in the model because the association between BMI and mortality differs substantially by age (35), and BMI in middle age is more strongly associated with mortality than is BMI later in life (36). (In 1982, the average age of the CPS-II Nutrition Cohort participants was 54 years for men and 52 years for women.) In addition, adjustment for BMI in 1982 had a larger effect on the hazard ratio than did adjustment for BMI in 1992.

RESULTS

Weight cycling was a prevalent behavior among CPS-II Nutrition Cohort participants. A total of 42% of men and 56.8% of women reported intentionally losing and regaining at least 10 pounds 1 or more times in their lifetime. Although the majority of weight cyclers reported between 1 and 4 weight cycles (30.6% of men and 36.7% of women), some men (1.3%) and women (3.4%) reported weight cycling 20 times or more.

Age-adjusted frequencies of baseline characteristics of the CPS-II Nutrition Cohort participants by number of weight cycles are shown in Table 1. Compared with noncyclers, both male and female weight cyclers were more likely to be younger, to be former smokers, and to have a history of diabetes or high blood pressure. Weight cyclers were also less likely to be current or never smokers and were more likely to have a higher BMI at 18 years of age, in 1982, and in 1992 and to have gained more weight between 18 years of age and 1992 and between 1982 and 1992. Female weight cyclers were also more likely to have a higher energy intake (kcal/day) and to drink less alcohol, whereas male weight cyclers exercised slightly more. For most of these characteristics, the difference between noncyclers and weight cyclers increased with increasing numbers of weight cycles.

Table 1.

Age-Standardizeda Means and Frequencies of Selected Characteristics of Men and Women, by Weight Cycling Status, Cancer Prevention Study II Nutrition Cohort, 1992

Variable Number of Weight Cycles
 
Men
 
Women
 
0 (n = 32,451)
 
1–4 (n = 17,121)
 
5–9 (n = 3,520)
 
10–19 (n = 2,154)
 
≥20 (n = 737)
 
0 (n = 28,823)
 
1–4 (n = 24,445)
 
5–9 (n = 6,414)
 
10–19 (n = 4,696)
 
≥20 (n = 2,277)
 
Mean Mean Mean Mean Mean Mean Mean Mean Mean Mean 
Age in 1992, years  64.3  62.8  61.7  61.5  60.8  62.9  61.5  60.5  60.1  59.5 
Race                     
    White 97.1  97.8  98.3  98.2  97.7  97.1  97.6  97.9  98.1  98.2  
    Black 1.3  1.1  1.0  0.8  1.5  1.3  1.4  1.4  1.4  1.0  
    Other/missing 1.6  1.1  0.7  1.0  0.6  1.6  1.0  0.7  0.5  0.8  
Educational level                     
    Some high school 8.0  6.4  5.6  4.8  6.1  4.8  4.6  4.7  5.1  5.7  
    High school graduate 20.1  16.9  15.2  15.7  11.9  32.0  32.5  32.5  30.8  28.3  
    Some college 24.9  25.4  24.7  28.3  29.9  29.5  31.5  32.0  33.8  38.1  
    College graduate or more 46.4  50.6  53.9  50.4  51.8  33.1  30.7  30.3  29.7  27.0  
    Missing 0.6  0.7  0.6  0.8  0.3  0.6  0.7  0.5  0.6  0.9  
Smoking status                     
    Never 36.9  31.5  31.8  30.7  33.0  57.3  55.3  52.9  51.8  48.2  
    Current 10.7  6.5  5.7  5.9  5.8  9.6  7.4  6.9  6.7  6.8  
    Former 51.5  61.2  61.6  62.4  60.6  31.6  35.9  38.8  40.3  43.3  
    Missing 0.9  0.8  0.9  1.0  0.6  1.5  1.4  1.4  1.2  1.7  
History of diabetes 5.1  9.4  11.4  12.1  14.7  2.9  5.3  7.2  8.8  9.9  
History of hypertension 28.2  40.0  44.0  46.6  48.4  23.6  33.1  39.0  41.4  42.0  
Postmenopausal hormone use in 1992                     
    Never           43.1  43.3  43.2  43.0  43.0  
    Current           33.8  31.8  30.6  32.0  29.2  
    Former           17.3  19.1  20.6  19.6  21.1  
    Ever/unknown           5.8  5.8  5.6  5.4  6.7  
Alcohol consumption, g/day  11.6  11.2  11.1  11.0  11.9  5.4  4.4  4.0  3.8  3.6 
Energy intake, kcal/day  1,828  1,786  1,787  1,807  1,866  1,354  1,357  1,386  1,385  1,449 
BMIb at 18 years of age  21.3  22.4  23.3  23.7  24.6  19.9  20.9  21.7  22.2  22.8 
BMI in 1982  25.0  27.1  28.2  28.8  29.9  22.4  25.0  26.8  27.8  28.9 
BMI in 1992  25.2  27.7  29.0  29.9  30.9  23.3  26.5  28.6  29.7  31.1 
Exercise, metabolic equivalent hours/week  13.3  13.1  13.5  13.9  13.5  12.3  11.8  11.6  11.6  12.3 
Weight change from 18 years of age to 1982, pounds  25.9  33.4  34.6  36.3  37.6  15.1  24.4  30.7  32.9  35.7 
Weight change from 1982 to 1992, pounds  1.8  4.2  5.9  8.0  7.3  5.1  8.5  10.4  11.7  13.1 
Variable Number of Weight Cycles
 
Men
 
Women
 
0 (n = 32,451)
 
1–4 (n = 17,121)
 
5–9 (n = 3,520)
 
10–19 (n = 2,154)
 
≥20 (n = 737)
 
0 (n = 28,823)
 
1–4 (n = 24,445)
 
5–9 (n = 6,414)
 
10–19 (n = 4,696)
 
≥20 (n = 2,277)
 
Mean Mean Mean Mean Mean Mean Mean Mean Mean Mean 
Age in 1992, years  64.3  62.8  61.7  61.5  60.8  62.9  61.5  60.5  60.1  59.5 
Race                     
    White 97.1  97.8  98.3  98.2  97.7  97.1  97.6  97.9  98.1  98.2  
    Black 1.3  1.1  1.0  0.8  1.5  1.3  1.4  1.4  1.4  1.0  
    Other/missing 1.6  1.1  0.7  1.0  0.6  1.6  1.0  0.7  0.5  0.8  
Educational level                     
    Some high school 8.0  6.4  5.6  4.8  6.1  4.8  4.6  4.7  5.1  5.7  
    High school graduate 20.1  16.9  15.2  15.7  11.9  32.0  32.5  32.5  30.8  28.3  
    Some college 24.9  25.4  24.7  28.3  29.9  29.5  31.5  32.0  33.8  38.1  
    College graduate or more 46.4  50.6  53.9  50.4  51.8  33.1  30.7  30.3  29.7  27.0  
    Missing 0.6  0.7  0.6  0.8  0.3  0.6  0.7  0.5  0.6  0.9  
Smoking status                     
    Never 36.9  31.5  31.8  30.7  33.0  57.3  55.3  52.9  51.8  48.2  
    Current 10.7  6.5  5.7  5.9  5.8  9.6  7.4  6.9  6.7  6.8  
    Former 51.5  61.2  61.6  62.4  60.6  31.6  35.9  38.8  40.3  43.3  
    Missing 0.9  0.8  0.9  1.0  0.6  1.5  1.4  1.4  1.2  1.7  
History of diabetes 5.1  9.4  11.4  12.1  14.7  2.9  5.3  7.2  8.8  9.9  
History of hypertension 28.2  40.0  44.0  46.6  48.4  23.6  33.1  39.0  41.4  42.0  
Postmenopausal hormone use in 1992                     
    Never           43.1  43.3  43.2  43.0  43.0  
    Current           33.8  31.8  30.6  32.0  29.2  
    Former           17.3  19.1  20.6  19.6  21.1  
    Ever/unknown           5.8  5.8  5.6  5.4  6.7  
Alcohol consumption, g/day  11.6  11.2  11.1  11.0  11.9  5.4  4.4  4.0  3.8  3.6 
Energy intake, kcal/day  1,828  1,786  1,787  1,807  1,866  1,354  1,357  1,386  1,385  1,449 
BMIb at 18 years of age  21.3  22.4  23.3  23.7  24.6  19.9  20.9  21.7  22.2  22.8 
BMI in 1982  25.0  27.1  28.2  28.8  29.9  22.4  25.0  26.8  27.8  28.9 
BMI in 1992  25.2  27.7  29.0  29.9  30.9  23.3  26.5  28.6  29.7  31.1 
Exercise, metabolic equivalent hours/week  13.3  13.1  13.5  13.9  13.5  12.3  11.8  11.6  11.6  12.3 
Weight change from 18 years of age to 1982, pounds  25.9  33.4  34.6  36.3  37.6  15.1  24.4  30.7  32.9  35.7 
Weight change from 1982 to 1992, pounds  1.8  4.2  5.9  8.0  7.3  5.1  8.5  10.4  11.7  13.1 

Abbreviation: BMI, body mass index.

a

Standardized to the age distribution of men or women in the cohort, respectively.

b

Weight (kg)/height (m)2.

The associations between weight cycling and mortality are shown in Table 2. In age-adjusted models, there was a dose-related statistically significant positive association between the number of weight cycles and the risk of all-cause mortality in men and in women. These associations were attenuated but remained statistically significant after adjustment for typical mortality risk factors, such as current smoking. However, after additional adjustment for BMI in 1982 and weight change between 18 years of age and 1982, low levels of weight cycling (1–4 or 5–9 weight cycles in men and 1–4 weight cycles in women) were statistically significantly inversely associated with all-cause mortality. All other levels of weight cycling were not associated with all-cause mortality rates in either men or women. In the fully adjusted models, weight cycling at any level except 1–4 times was not associated with death from cardiovascular disease in either men or women. In men, weight cycling 5–9 times was inversely associated with death from cancer and weight cycling 1–4 times or 5–9 times was inversely associated with death from other causes. No other weight cycling categories in men and no categories in women were associated with death from cancer or other causes.

Table 2.

Relative Risk of Death in Men and Women by Number of Weight Cycles in the Cancer Prevention Study II Nutrition Cohort, 1992–2008

Cause of Death and No. of Weight Cycles Men
 
Women
 
No. of Deaths RR95% CI RR95% CI RR95% CI No. of Deaths RR95% CI RR 95% CI RR95% CI 
All causes               
    0 9,272 1.00 Referent 1.00 Referent 1.00 Referent 4,612 1.00 Referent 1.00 Referent 1.00 Referent 
    1–4 4,336 1.03 0.99, 1.07 0.99 0.95, 1.02 0.93 0.89, 0.97 3,547 1.05 1.00, 1.09 0.99 0.94, 1.03 0.93 0.89, 0.98 
    5–9 802 1.03 0.96, 1.11 0.97 0.90, 1.05 0.88 0.81, 0.94 925 1.17 1.09, 1.26 1.06 0.99, 1.14 0.95 0.88, 1.02 
    10–19 534 1.17 1.07, 1.28 1.09 1.00, 1.19 0.96 0.88, 1.05 661 1.22 1.12, 1.32 1.07 0.99, 1.17 0.93 0.85, 1.01 
    ≥20 194 1.35 1.17, 1.56 1.22 1.06, 1.41 1.03 0.89, 1.19 342 1.41 1.26, 1.58 1.19 1.06, 1.33 0.99 0.88, 1.12 
        P for trend  <0.0001  0.007  0.30   <0.0001  0.0003  0.65  
Cardiovascular disease               
    0 3,165 1.00 Referent 1.00 Referent 1.00 Referent 1,394 1.00 Referent 1.00 Referent 1.00 Referent 
    1–4 1,556 1.12 1.05, 1.19 1.03 0.97, 1.10 0.93 0.87, 0.99 1,067 1.11 1.02, 1.20 0.99 0.91, 1.07 0.91 0.83, 0.99 
    5–9 310 1.24 1.10, 1.40 1.10 0.98, 1.24 0.93 0.82, 1.05 275 1.27 1.12, 1.45 1.06 0.93, 1.21 0.91 0.79, 1.04 
    10–19 197 1.34 1.16, 1.55 1.18 1.02, 1.37 0.97 0.83, 1.13 205 1.42 1.22, 1.64 1.14 0.98, 1.32 0.93 0.80, 1.09 
    ≥20 80 1.76 1.41, 2.20 1.48 1.19, 1.86 1.14 0.91, 1.44 114 1.83 1.51, 2.22 1.40 1.16, 1.71 1.11 0.91, 1.36 
        P for trend  <0.0001  <0.0001  0.70   <0.0001  0.0002  0.47  
Cancer               
    0 3,011 1.00 Referent 1.00 Referent 1.00 Referent 1,660 1.00 Referent 1.00 Referent 1.00 Referent 
    1–4 1,446 0.99 0.93, 1.05 1.01 0.95, 1.08 0.97 0.90, 1.03 1,310 1.00 0.93, 1.07 0.98 0.91, 1.06 0.93 0.86, 1.01 
    5–9 245 0.88 0.77, 1.00 0.90 0.79, 1.02 0.83 0.72, 0.95 340 1.05 0.94, 1.19 1.03 0.91, 1.16 0.94 0.83, 1.07 
    10–19 168 1.01 0.86, 1.18 1.02 0.87, 1.20 0.93 0.79, 1.09 236 1.03 0.90, 1.18 0.99 0.86, 1.14 0.89 0.77, 1.03 
    ≥20 58 1.08 0.83, 1.40 1.09 0.84, 1.42 0.96 0.74, 1.26 122 1.15 0.95, 1.38 1.07 0.88, 1.29 0.94 0.78, 1.15 
        P for trend  0.86  0.85  0.17   0.13  0.55  0.34  
Other               
    0 3,096 1.00 Referent 1.00 Referent 1.00 Referent 1,558 1.00 Referent 1.00 Referent 1.00 Referent 
    1–4 1,334 0.97 0.91, 1.04 0.91 0.86, 0.98 0.89 0.83, 0.95 1,170 1.05 0.98, 1.14 0.98 0.91, 1.06 0.93 0.86, 1.02 
    5–9 247 1.00 0.88, 1.14 0.92 0.80, 1.05 0.86 0.75, 0.99 310 1.23 1.08, 1.39 1.11 0.98, 1.25 0.98 0.86, 1.12 
    10–19 169 1.18 1.01, 1.37 1.07 0.92, 1.25 0.99 0.84, 1.16 220 1.28 1.11, 1.48 1.12 0.97, 1.30 0.96 0.82, 1.12 
    ≥20 56 1.26 0.97, 1.64 1.11 0.85, 1.45 0.98 0.75, 1.29 106 1.41 1.15, 1.71 1.18 0.96, 1.44 0.97 0.79, 1.19 
        P for trend  0.03  0.73  0.44   <0.0001  0.02  0.84  
Cause of Death and No. of Weight Cycles Men
 
Women
 
No. of Deaths RR95% CI RR95% CI RR95% CI No. of Deaths RR95% CI RR 95% CI RR95% CI 
All causes               
    0 9,272 1.00 Referent 1.00 Referent 1.00 Referent 4,612 1.00 Referent 1.00 Referent 1.00 Referent 
    1–4 4,336 1.03 0.99, 1.07 0.99 0.95, 1.02 0.93 0.89, 0.97 3,547 1.05 1.00, 1.09 0.99 0.94, 1.03 0.93 0.89, 0.98 
    5–9 802 1.03 0.96, 1.11 0.97 0.90, 1.05 0.88 0.81, 0.94 925 1.17 1.09, 1.26 1.06 0.99, 1.14 0.95 0.88, 1.02 
    10–19 534 1.17 1.07, 1.28 1.09 1.00, 1.19 0.96 0.88, 1.05 661 1.22 1.12, 1.32 1.07 0.99, 1.17 0.93 0.85, 1.01 
    ≥20 194 1.35 1.17, 1.56 1.22 1.06, 1.41 1.03 0.89, 1.19 342 1.41 1.26, 1.58 1.19 1.06, 1.33 0.99 0.88, 1.12 
        P for trend  <0.0001  0.007  0.30   <0.0001  0.0003  0.65  
Cardiovascular disease               
    0 3,165 1.00 Referent 1.00 Referent 1.00 Referent 1,394 1.00 Referent 1.00 Referent 1.00 Referent 
    1–4 1,556 1.12 1.05, 1.19 1.03 0.97, 1.10 0.93 0.87, 0.99 1,067 1.11 1.02, 1.20 0.99 0.91, 1.07 0.91 0.83, 0.99 
    5–9 310 1.24 1.10, 1.40 1.10 0.98, 1.24 0.93 0.82, 1.05 275 1.27 1.12, 1.45 1.06 0.93, 1.21 0.91 0.79, 1.04 
    10–19 197 1.34 1.16, 1.55 1.18 1.02, 1.37 0.97 0.83, 1.13 205 1.42 1.22, 1.64 1.14 0.98, 1.32 0.93 0.80, 1.09 
    ≥20 80 1.76 1.41, 2.20 1.48 1.19, 1.86 1.14 0.91, 1.44 114 1.83 1.51, 2.22 1.40 1.16, 1.71 1.11 0.91, 1.36 
        P for trend  <0.0001  <0.0001  0.70   <0.0001  0.0002  0.47  
Cancer               
    0 3,011 1.00 Referent 1.00 Referent 1.00 Referent 1,660 1.00 Referent 1.00 Referent 1.00 Referent 
    1–4 1,446 0.99 0.93, 1.05 1.01 0.95, 1.08 0.97 0.90, 1.03 1,310 1.00 0.93, 1.07 0.98 0.91, 1.06 0.93 0.86, 1.01 
    5–9 245 0.88 0.77, 1.00 0.90 0.79, 1.02 0.83 0.72, 0.95 340 1.05 0.94, 1.19 1.03 0.91, 1.16 0.94 0.83, 1.07 
    10–19 168 1.01 0.86, 1.18 1.02 0.87, 1.20 0.93 0.79, 1.09 236 1.03 0.90, 1.18 0.99 0.86, 1.14 0.89 0.77, 1.03 
    ≥20 58 1.08 0.83, 1.40 1.09 0.84, 1.42 0.96 0.74, 1.26 122 1.15 0.95, 1.38 1.07 0.88, 1.29 0.94 0.78, 1.15 
        P for trend  0.86  0.85  0.17   0.13  0.55  0.34  
Other               
    0 3,096 1.00 Referent 1.00 Referent 1.00 Referent 1,558 1.00 Referent 1.00 Referent 1.00 Referent 
    1–4 1,334 0.97 0.91, 1.04 0.91 0.86, 0.98 0.89 0.83, 0.95 1,170 1.05 0.98, 1.14 0.98 0.91, 1.06 0.93 0.86, 1.02 
    5–9 247 1.00 0.88, 1.14 0.92 0.80, 1.05 0.86 0.75, 0.99 310 1.23 1.08, 1.39 1.11 0.98, 1.25 0.98 0.86, 1.12 
    10–19 169 1.18 1.01, 1.37 1.07 0.92, 1.25 0.99 0.84, 1.16 220 1.28 1.11, 1.48 1.12 0.97, 1.30 0.96 0.82, 1.12 
    ≥20 56 1.26 0.97, 1.64 1.11 0.85, 1.45 0.98 0.75, 1.29 106 1.41 1.15, 1.71 1.18 0.96, 1.44 0.97 0.79, 1.19 
        P for trend  0.03  0.73  0.44   <0.0001  0.02  0.84  

Abbreviations: CI, confidence interval; RR, relative risk.

a

Age-adjusted model.

b

Multivariate-adjusted model stratified by age that included alcohol consumption, race, smoking status, educational level, physical activity level, history of high blood pressure, history of diabetes, and total energy intake.

c

Multivariate-adjusted model stratified by age that included alcohol consumption, race, smoking status, educational level, physical activity level, body mass index in 1982, weight change from 18 years of age to 1982, history of high blood pressure, history of diabetes, and total energy intake.

To determine whether the association between weight cycling and all-cause mortality varied across categories of BMI in middle age, analyses were stratified by participants’ BMIs in 1982. These results are shown in Figure 1. Weight cycling at any level was not associated with mortality in normal-weight (BMI 18.5–24.9) or obese (BMI ≥30) men. Among men who were overweight (BMI 25–29.9) during middle age, cycling 1–4 and 5–9 times was associated with a statistically significant lower risk of death (7% and 12%, respectively). No other levels of weight cycling in overweight men were associated with all-cause mortality. Although no increased risk of mortality was found for women in any weight category, weight cycling for 1–4 or 10–19 cycles by overweight women was associated with a statistically significant decreased risk of mortality (12% and 21%, respectively), but no trend was observed. Results were also examined by weight change from 18 years of age to 1982 (middle age). No significant associations were found for either men or women who maintained their weight (lost 5 pounds to gained 5 pounds) or who gained any amount of weight these analyses (data not shown).

Figure 1.

Risk of death from all causes and weight cycling stratified by body mass index (weight (kg)/height (m)2) in Cancer Prevention Study II Nutrition Cohort participants in 1982. The associations of 1–4 (open circles), 5–9 (filled circles), 10–19 (open diamonds), and 20 or more (filled diamonds) cycles with all-cause mortality relative to participants who did not experience weight cycling is shown among men (A) and women (B). The hazard ratios and 95% confidence intervals were determined using a multivariable-adjusted model that was stratified by age and included alcohol use, race, smoking status, educational level, physical activity level, body mass index in 1982, weight change from 18 years of age to 1982, history of high blood pressure, history of diabetes, and total energy intake. Bars, 95% confidence interval.

Figure 1.

Risk of death from all causes and weight cycling stratified by body mass index (weight (kg)/height (m)2) in Cancer Prevention Study II Nutrition Cohort participants in 1982. The associations of 1–4 (open circles), 5–9 (filled circles), 10–19 (open diamonds), and 20 or more (filled diamonds) cycles with all-cause mortality relative to participants who did not experience weight cycling is shown among men (A) and women (B). The hazard ratios and 95% confidence intervals were determined using a multivariable-adjusted model that was stratified by age and included alcohol use, race, smoking status, educational level, physical activity level, body mass index in 1982, weight change from 18 years of age to 1982, history of high blood pressure, history of diabetes, and total energy intake. Bars, 95% confidence interval.

Smoking influences both body weight (37) and mortality risk (38), and adjusting for it in the statistical model may not adequately control for its effect on the association between weight cycling and mortality. Therefore, we performed a sensitivity analysis that was restricted to never smokers. The associations were null and unchanged (data not shown). Limiting the analysis to men and women who were 70 years of age or younger at baseline in 1992 also did not change the association between weight cycling and all-cause mortality.

DISCUSSION

In the present large prospective study, high levels of weight cycling were not associated with increased all-cause mortality rates in either men or women after adjustment for BMI and other confounding factors. However, low levels of weight cycling (1–4 or 5–9 weight cycles in men and 1–4 weight cycles in women) were inversely associated with all-cause mortality. The importance of adequately controlling for body weight and weight change at middle age, which can influence mortality (39, 40), is illustrated by the differences in the age-adjusted associations after adjustment for these and other covariates. These findings suggest that, when considered independently of the BMI and weight change, weight cycling does not increase the risk of premature death.

No association was found between weight cycling and death from cardiovascular disease for any category of weight cycling except the lowest. Most categories of weight cycling were also not associated with death from cancer or other causes. The statistically significant inverse association of 5–9 weight cycles with cancer death in men was likely due to chance because there was no evidence of a significantly reduced risk of death from cancer for either higher or lower levels of weight cycling. The significant associations of 1–4 and 5–9 weight cycles with death from other causes in men may reflect a true reduced risk, although the broad nature of this endpoint precludes a meaningful interpretation of this finding. A large study is needed to fully assess the specific causes of death.

The findings presented here are consistent with those of the only other study that considered the intentionality of weight loss when defining weight cycling. Field et al. (16) reported that weight cycling was not associated with all-cause or cardiovascular disease mortality for women in the Nurses’ Health Study. However, similar to our findings for men and women with low numbers of weight cycles, Field et al. (16) found that intentionally losing at least 4.5 kg (10 pounds) at least 3 times was associated with a statistically significant 17% lower risk of all-cause mortality compared with noncyclers (16). Why low levels of weight cycling might be associated with a reduced risk of premature death is not readily apparent.

The association between weight cycling and all-cause mortality did not vary by BMI at middle age (in 1982) or by weight change between 18 years of age and 1982. To our knowledge, this fact has never been investigated before and indicates that potential effects of weight cycling relevant to mortality do not differ in lean, overweight, or obese individuals and are not differentially affected by weight changes during adulthood. The association between weight cycling and mortality was also not confounded by smoking, as indicated by the sensitivity analysis in which only nonsmokers were included.

The present study has a number of strengths, including its prospective nature and the large number of weight cyclers of both sexes. To our knowledge, it includes the largest number of weight cyclers of any study reported to date and is the first to investigate the association between weight cycling initiated by intentional weight loss and mortality in men. The large study population allowed us to examine the associations between 4 levels of this behavior and mortality in men and women separately. These levels covered a broader range of number of weight cycles than other studies, with the top category of 20 or more weight cycles, which was twice that of the maximum category of any previous report (23). Because information was collected on both purposeful weight loss and subsequent regain, we were able to define weight cycles based on both phases rather than just assuming regain, as has been done in many studies (5, 16, 41–44). The availability of data on BMI at middle age, weight change, and other covariates for the CPS-II Nutrition Cohort participants was critical for separating the influence of these factors on mortality from that of weight cycling.

An important limitation of the present study is the lack of information on the timing, magnitude, and duration of each phase of the weight cycles, and it is unclear whether this behavior began during adolescence or adulthood. Therefore, whether the association of weight cycling with mortality differs during various phases of life could not be assessed. Similarly, without knowing how much weight was lost in each cycle, we were unable to determine whether the associations of mortality with larger weight loss cycles differed from those with smaller weight loss cycles. In the present study, weight cycling history was self-reported. Although this may have resulted in some misclassification, there is no apparent reason why it would be differential with respect to mortality. In addition, the weight cycling responses have not been validated. However, 75% of the weight cyclers reported equal numbers of times they purposely lost weight and regained weight, which would be expected given that most people who lose weight do not maintain that weight loss (45).

In summary, the results of the present study indicate that weight cycling, independent of BMI and weight gain, does not increase the overall risk of mortality. These results apply to participants with varying numbers of weight cycles and to both men and women of all body weights. Thus, weight loss attempts by overweight and obese individuals should be encouraged even though weight lost may often be regained.

Abbreviations

    Abbreviations
  • BMI

    body mass index

  • CPS-II

    Cancer Prevention Study II

Author affiliation: Epidemiology Research Program, American Cancer Society, Atlanta, Georgia.

Conflict of interest: none declared.

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