Dicarbonyl compounds are highly reactive precursors of advanced glycation end products (AGE), produced endogenously, present in certain foods and formed during food processing. AGE contribute to the development of adverse metabolic outcomes, but health effects of dietary dicarbonyls are largely unexplored. We investigated associations between three dietary dicarbonyl compounds, methylglyoxal (MGO), glyoxal (GO) and 3-deoxyglucosone (3-DG), and body weight changes in European adults. Dicarbonyl intakes were estimated using food composition database from 263 095 European Prospective Investigation into Cancer and Nutrition–Physical Activity, Nutrition, Alcohol, Cessation of Smoking, Eating Out of Home in Relation to Anthropometry participants with two body weight assessments (median follow-up time = 5·4 years). Associations between dicarbonyls and 5-year body-weight changes were estimated using mixed linear regression models. Stratified analyses by sex, age and baseline BMI were performed. Risk of becoming overweight/obese was assessed using multivariable-adjusted logistic regression. MGO intake was associated with 5-year body-weight gain of 0·089 kg (per 1-sd increase, 95 % CI 0·072, 0·107). 3-DG was inversely associated with body-weight change (–0·076 kg, −0·094, −0·058). No significant association was observed for GO (0·018 kg, −0·002, 0·037). In stratified analyses, GO was associated with body-weight gain among women and older participants (above median of 52·4 years). MGO was associated with higher body-weight gain among older participants. 3-DG was inversely associated with body-weight gain among younger and normal-weight participants. MGO was associated with a higher risk of becoming overweight/obese, while inverse associations were observed for 3-DG. No associations were observed for GO with overweight/obesity. Dietary dicarbonyls are inconsistently associated with body weight change among European adults. Further research is needed to clarify the role of these food components in overweight and obesity, their underlying mechanisms and potential public health implications.

High-quality diets have been found to be beneficial in preventing long-term weight gain. However, concurrent changes in diet quality and body weight over time have rarely been reported. We examined the association between 10-year changes in diet quality and body weight in the Multiethnic Cohort Study. Analyses included 53 977 African Americans, Native Hawaiians, Japanese Americans, Latinos and Whites, who completed both baseline (1993–1996, 45–69 years) and 10-year follow-up (2003–2008) surveys including a FFQ and had no history of heart disease or cancer. Using multivariable regression, weight changes were regressed on changes in four diet quality indexes, Healthy Eating Index-2015, Alternative Healthy Eating Index-2010, alternate Mediterranean Diet and Dietary Approaches to Stop Hypertension scores. Mean weight change over 10 years was 1·2 (sd 6·8) kg in men and 1·5 (sd 7·2) kg in women. Compared with stable diet quality (< 0·5 sd change), the greatest increase (≥ 1 sd increase) in the diet scores was associated with less weight gain (by 0·55–1·17 kg in men and 0·62–1·31 kg in women). Smaller weight gain with improvement in diet quality was found in most subgroups by race/ethnicity, baseline age and baseline BMI. The inverse association was stronger in younger age and higher BMI groups. Ten-year improvement in diet quality was associated with a smaller weight gain, which varied by race/ethnicity and baseline age and BMI. Our findings suggest that maintaining a high-quality diet and improving diet quality over time may prevent excessive weight gain.

Dietary patterns, which represent a broader picture of food and nutrient consumption, have gained increasing interest over the last decades. In a cohort design, we followed 27 544 women aged 29–49 years from baseline in 1991–1992. We collected data from an FFQ at baseline and body weight (BW) and waist circumference (WC) data both at baseline and at follow-up in 2003. We calculated the Mediterranean diet score (MDS, ranging from 0 to 9) and the Nordic diet score (NDS, ranging from 0 to 6). We used linear regression to examine the association between MDS and NDS (exposures) with subsequent BW change (ΔBW) and WC change (ΔWC) (outcomes) both continuously and categorically. Higher adherence to the MDS or NDS was not associated with ΔBW. The multivariable population average increment in BW was 0·03 kg (95 % CI −0·03, 0·09) per 1-point increase in MDS and 0·04 kg (95 % CI −0·02, 0·10) per 1-point increase in NDS. In addition, higher adherence to the MDS was not associated with ΔWC, with the multivariable population average increment per 1-point increase in MDS being 0·05 cm (95 % CI −0·03, 0·13). Higher adherence to the NDS was not significantly associated with gain in WC when adjusted for concurrent ΔBW. In conclusion, a higher adherence to the MDS or NDS was not associated with changes in average BW or WC in the present cohort followed for 12 years.

The existence of a set-point for homeostatic control of human body weight is uncertain. To investigate its existence, technically difficult determinations of energy expenditure must be performed: this has resulted in contradictory reports. The present study was performed with new methods in two stages (77 and 133d respectively). Two healthy male subjects with rigorously controlled physical activity ingested three standardized diets of processed foods from the same manufacturer. Hypo-, iso- and hyperenergetic diets containing 6255kJ (1494kcal), 10073kJ (2406kcal) and 13791kJ (3294kcal) respectively were ingested during alternate periods; changes in body weight were measured. A new index of energy expenditure was calculated as the amount of weight lost in an 8h overnight period (WL8H). A digital scale was used in stage 1 and a mechanical scale in stage 2. The change in body weight in response to the isoenergetic diet differed according to the circumstances. In basal conditions, it was associated with weight stability. After weight loss from energy restriction, the isoenergetic diet led to weight gain. After weight gain from overeating, it led to weight loss. Diets of higher energy content were associated with greater WL8H (F>20; P<0·0001 for both subjects). Measurement variability was lower using a mechanical scale. The present study demonstrates the existence of a homeostatic control of human weight and describes a new index of energy expenditure measured in weight units. It also demonstrates that strict dietary supervision for months is possible. Investigation of the human body weight set-point is vital in understanding obesity.