Does dieting make you fat? A twin study.

OBJECTIVE: To investigate whether the paradoxical weight gain associated with dieting is better related to genetic propensity to weight gain than to the weight loss episodes themselves. SUBJECTS: Subjects included 4129 individual twins from the population-based FinnTwin16 study (90% of twins born in Finland 1975-1979). Weight and height were obtained from longitudinal surveys at 16, 17, 18 and 25 years, and number of lifetime intentional weight loss (IWL) episodes of more than 5 kg at 25 years. RESULTS: IWLs predicted accelerated weight gain and risk of overweight. The odds of becoming overweight (body mass index (BMI)≥ 25 kg m(-2)) by 25 years were significantly greater in subjects with one (OR 1.8, 95% CI 1.3-2.6, and OR 2.7, 1.7-4.3 in males and females, respectively), or two or more (OR 2.0, 1.3-3.3, and OR 5.2, 3.2-8.6, in males and females, respectively), IWLs compared with subjects with no IWL. In MZ pairs discordant for IWL, co-twins with at least one IWL were 0.4 kg m(-2) (P=0.041) heavier at 25 years than their non-dieting co-twins (no differences in baseline BMIs). In DZ pairs, co-twins with IWLs gained progressively more weight than non-dieting co-twins (BMI difference 1.7 kg m(-2) at 16 years and 2.2 kg m(-2) at 25 years, P<0.001). CONCLUSION: Our results suggest that frequent IWLs reflect susceptibility to weight gain, rendering dieters prone to future weight gain. The results from the MZ pairs discordant for IWLs suggest that dieting itself may induce a small subsequent weight gain, independent of genetic factors.

Changes in body mass index and measures of abdominal obesity in Finnish adults between 1992 and 2007, the National FINRISK Study.

UNLABELLED: What is already known about this subject • Recent obesity trends across the world in adults are mixed, varying from showing signs of levelling off to a continuously increasing prevalence. • Secular trends in body mass index (BMI) and waist circumference may vary by sex and age. • Relying exclusively on BMI data may lead to underestimate the obesity epidemic. What this study adds • Adverse trends in obesity indicators have continued in Finland in the 2000s. • In older men, BMI remained quite stable and in older women BMI has decreased since 1997. • Steep upward trends in abdominal obesity (waist circumference and waist-to-height ratio, WHtR) have taken place in both men and women and in all age groups, especially during the past 10 years. • The impact of BMI adjustment on trends in abdominal obesity varied by age such that increases in BMI-adjusted waist circumference and WHtR were more prominent in older age groups. SUMMARY: Signs that obesity trends will level off at the turn of the 21st century have been reported. In these studies, however, the definition of obesity has been based only on body mass index (BMI). We investigated obesity trends among Finnish adults over recent years by using BMI, waist circumference and waist-to-height ratio as indicators for obesity. Data were derived from the national FINRISK surveys, which are cross-sectional population surveys conducted at 5-year intervals between 1992 and 2007. Altogether, 20 551 randomly selected men and women aged 25-64 years participated in health examinations, where weight, height, and waist and hip circumferences were measured by trained nurses. Mean BMI increased in younger men and women (aged 25-44 years) between 1992 and 2007, whereas in older men, BMI remained quite stable and in older women BMI has decreased since 1997. Nevertheless, mean waist circumference and waist-to-height ratio increased in both men and women over the 15-year period. The upward trends took place in all age groups, especially during the past 10 years. Adverse trends in obesity indicators have continued in Finland in the 2000s. In particular, concerns are related to steep upward trends in abdominal obesity.

Body composition in psychotic disorders: a general population survey.

BACKGROUND: The literature suggests an association between obesity and schizophrenia but fat mass and fat-free mass, which have been shown to be more predictive of all-cause mortality than only waist circumference and obesity [body mass index (BMI) 30 kg/m2], have not been reported in psychotic disorders. We examined the detailed body composition of people with different psychotic disorders in a large population-based sample. METHOD: We used a nationally representative sample of 8082 adult Finns aged 30 years with measured anthropometrics (height, weight, waist circumference, fat percentage, fat-free mass and segmental muscle mass). Psychiatric diagnoses were based on a consensus procedure utilizing the Structured Clinical Interview for DSM-IV (SCID)-interview, case-notes and comprehensive register data. RESULTS: Schizophrenia (including schizo-affective disorder) was associated with obesity [odds ratio (OR) 2.3, 95% confidence interval (CI) 1.5-3.6], abdominal obesity (waist circumference 88 cm for women, 102 cm for men) (OR 2.2, 95% CI 1.3-3.6) and with higher fat percentage (mean difference 3.8%, 95% CI 2.0-5.7%), adjusted for age and gender, than in the remaining sample. The associations between schizophrenia and low fat-free mass and decreased muscle mass on trunk and upper limbs became statistically significant after adjusting for BMI. After further adjusting for current antipsychotic medication, education, diet and smoking, schizophrenia remained associated with obesity (OR 1.9, 95% CI 1.1-3.6) and abdominal obesity (OR 3.8, 95% CI 1.5-9.4). Participants with affective psychoses did not differ from the general population. CONCLUSIONS: Individuals with schizophrenia have metabolically unfavorable body composition, comprising abdominal obesity, high fat percentage and low muscle mass. This leads to increased risk of metabolic and cardiovascular diseases.

Weight cycling of athletes and subsequent weight gain in middleage.

OBJECTIVE: To study the effects of repeated cycles of weight loss and regain as young adults on long-term weight development. DESIGN: A follow-up study with questionnaires in 1985, 1995 and 2001. SETTING: Finland. SUBJECTS: A national cohort of 1838 male elite athletes who had represented Finland in major international sport competitions in 1920-1965, including 370 men engaged in sports in which weight-related performance classes are associated with weight cycling (boxers, weight lifters and wrestlers; further called as weight cyclers), and 834 matched control men with no athletic background. OUTCOME MEASURE: Weight change since the age of 20 years, body mass index (BMI) and prevalence of obesity and overweight. RESULTS: The weight cyclers gained 5.2 BMI units from age 20 years to their maximum mean weight, which was at age 58.7 years. Corresponding figures for the controls were 4.2 BMI units at 58.5 years and for other athletes 3.3 BMI units at age 62.5 years. The proportion of obese (BMI> or =30 kg/m(2)) subjects was greatest among the weight cyclers both in 1985 and 1995. In 2001, the weight cyclers were more often obese than other athletes, but did not differ from the controls. The odds ratio for the weight cyclers to be obese compared to other athletes in 1985 was 3.18 (95% confidence intervals 2.09-4.83), and compared to the controls 2.0 (1.35-2.96). The enhanced weight gain of the weight cyclers was not accounted for by present health habits (smoking, alcohol use, use of high-fat milk or physical activity) or weight at age 20 years. CONCLUSIONS: Repeated cycles of weight loss and regain appear to enhance subsequent weight gain and may predispose to obesity. Chronic dieting with weight cycling may be harmful for permanent weight control.

Intentional weight loss and smoking in young adults.

OBJECTIVE: To investigate whether current smoking and lifetime snuff use are associated with a lifetime history of major (>/=5 kg) intentional weight loss in young adults, and to examine the dependence of this association on familial factors. DESIGN: Cross-sectional population-based questionnaire survey of young adult Finnish twins participating in the fourth wave of the longitudinal FinnTwin-16-study in 2000-2002. SUBJECTS: A total of 4521 young adult Finnish twins aged 23-27 y. MEASUREMENTS: Questionnaire data on the number of intentional weight-loss episodes and on body mass index (BMI), cigarette smoking and snuff use, educational level, and number of subjects' own children. RESULTS: Current daily smoking was strongly associated with a history of two or more intentional major weight-loss episodes (lost >/=5 kg twice or more lifetime) both in women odds ratio (OR 1.87; 95%; confidence interval (CI) 1.39-2.50) and in men (OR 2.00; 95% CI 1.37-2.90). Frequent lifetime snuff use was statistically significantly associated with recurrent intentional weight loss episodes in men (OR 1.51; 95% CI 1.08-2.13). Among the twin pairs discordant for daily smoking, the smoking twin was more likely than the nonsmoking co-twin to have recurrent intentional weight-loss episodes (OR 1.57; 95% CI 1.03-2.41). These episodes were also strongly associated with high BMI. Education was inversely related to recurrent intentional weight-loss episodes in men. CONCLUSION: Tobacco use is strongly associated with a lifetime history of recurrent intentional major weight-loss episodes in early adulthood. This represents a major challenge to existing attitudes on smoking prevention and the promotion of healthful weight control.