Objective: Prevention would be the ideal public health strategy to face the current obesity epidemic. Adoption of healthy lifestyles during the first years of college or university could prevent the onset of weight gain associated with this period of acquired independence and eventually decrease the incidence of obesity. Design: Randomized-controlled trial over a period of 2 years. The subjects received an educational/behavioral intervention (small group seminars) designed to help maintain a healthy lifestyle or no specific intervention (control group). Subjects: One-hundred and fifteen non-obese freshmen in a Faculty of Medicine. Measurements: Anthropometric measurements, physical activity level, fitness level, food intake and lipid profile were recorded at predetermined intervals. Results: The control group gained weight, whereas the intervention group lost a slight amount of weight over 2 years. The difference between the two groups was 1.3 kg at the end of the follow-up, the trend of weight gain differing between the two groups during the 2-year intervention period (P ¼ 0.04). There was no detectable difference in fitness, physical activity level or total caloric intake between the two groups during follow-up. However, plasma triglyceride levels increased in the control group and decreased in the intervention group (P ¼ 0.04). Conclusion: In this randomized-controlled trial, a small-group seminar educational/behavioral intervention successfully prevents weight gain in normal weight young healthy university students. Such small absolute changes in body composition and lipid profile, if maintained over a prolonged period, could result in significant long-term health benefits for the general population (ClinicalTrial.gov registration number: NCT00306449).

Obesity has now reached epidemic proportions. Epidemiological studies in the past decades have shown that adults gain weight and adiposity from the early twenties until their sixties. In the paediatric population, growing numbers of children and adolescents put on unhealthy weight. Many environmental, socio-economical and biological determinants that predispose to weight gain have been identified thus far. The aim of the present review is to summarize the current knowledge on the role of the circulating levels of adipokines and other entero-insular hormones and biological markers of obesity to predict weight gain in humans. The review focuses on relationship between hormonal and biochemical markers (insulin, insulin-like growth factors, gastrointestinal hormones, leptin, adiponectin, resistin, inflammatory proteins and cytokines) and weight gain in prospective studies. The complex relationships displayed by these hormonal factors with future weight gain in humans are critically reviewed and integrative models are proposed. Overall, most of the studies reported to date made adjustments for baseline body mass index but failed to consider dietary intake and physical activity as confounding factors. Outstanding questions are raised and new directions for future prospective studies are proposed in order to improve our understanding of the role of biological determinants of energy balance and development of obesity in humans.

The aim of the study was to evaluate the influence of weight gain and changes in adiposity distribution on insulin resistance and circulating adiponectin variations over 4 years in free-living normal weight young adults. In this prospective observational cohort (n=42 women, 18 men), anthropometric measurements and blood samples were collected in the fasting state at baseline and at 4 years. Insulin resistance was estimated using the homeostatic model assessment (HOMA-IR). Circulating adiponectin levels were determined by radioimmunoassay. To investigate increase in adiposity more specifically, subsidiary analyses were performed in a subgroup of individuals (n=31) who gained adiposity over the course of the 4-year follow-up (defined as gain >1% in percent body fat). Regression analyses were performed to adjust for sex, age, parental education, lifestyle, and fitness levels. At baseline, the participants were young adults (age=20.0 years old) in the normal weight range [body mass index (BMI)=22.7 kg/m2 (IQR=21.1-24.4)]. Median change in body fat percentage was +1.4% (IQR=-0.3-3.4; p=0.01) and in waist circumference was +1.2 cm (IQR=-2.6-5.3; p=0.05). In the subgroup of individuals who gained more than 1% body fat, increase in HOMA-IR was associated with an increase in BMI (r=0.44; p=0.01; p<0.01 in fully adjusted model), while decrease in adiponectin levels was associated with an increase in waist circumference (r=-0.38; p=0.03) but this was no longer significant after adjustment for sex and other potential confounders (p=0.14). In a population of young adults, small variations in adiposity within the normal weight range were associated with increase in insulin resistance.