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Recent research: prevention & treatment of overweight with changed eating behaviours, energy density & breastfeeding

Here are six studies on eating and weight.  The first, by Maruyama and colleagues, demonstrates a strong association between both "eating until full" and "eating quickly" and the chances of being overweight.  The linked BMJ editorial by Denney-Wilson & Campbell discusses these findings further, including suggesting that "Clinicians should encourage parents to adopt a child led feeding strategy that acknowledges a child's desire to stop eating that begins from birth. Reassure parents that well children don't starve."  Unfortunately Llewellyn et al show that eating rate seems to be partly genetically determined - an even stronger reason to work hard to go against any tendency to gobble food.  The Denney-Wilson editorial gives other ways to encourage weight loss, and Leahy and colleagues underlines the value of one such approach - reducing the energy density (ED) of diets " ...  by decreasing fat and sugar and by increasing fruit and vegetables."  Children whose diet was changed in this way " ... consumed a consistent weight of foods and beverages over 2 d in both conditions (high energy & low energy), and therefore their energy consumption declined by 389 {+/-} 72 kcal (14%) in the lower-ED condition, a significant decrease (P < 0.0001)."  Similar approaches have been found helpful for adults too.  An interesting report by Baker and colleagues underlines the value of breastfeeding in helping mothers to lose excessive weight they may have put on during pregnancy.  Finally a freely viewable full text editorial by Shai & Stampfer consider the crucial question "Weight-loss diets - can you keep it off?"  They highlight that "The frequency of exercise after the diet program is the strongest predictor of weight loss maintenance, while television viewing is associated with weight gain. Current guidelines to prevent weight gain recommend 60 min per day of at least moderate-intensity physical activity." They also point out the challenging, but encouraging, finding that  " ... if the participants successfully maintained their weight loss for 2-5 y, the chance of longer-term success increased greatly."

Maruyama, K., S. Sato, et al. (2008). "The joint impact on being overweight of self reported behaviours of eating quickly and eating until full: cross sectional survey." BMJ 337(oct21_2): a2002-.  [Free Full Text]  
Objective: To examine whether eating until full or eating quickly or combinations of these eating behaviours are associated with being overweight. Design and participants: Cross sectional survey. Setting: Two communities in Japan. Participants 3287 adults (1122 men, 2165 women) aged 30-69 who participated in surveys on cardiovascular risk from 2003 to 2006. Main outcome measures: Body mass index (overweight greater than or equal to 25.0) and the dietary habits of eating until full (lifestyle questionnaire) and speed of eating (validated brief self administered questionnaire). Results: 571 (50.9%) men and 1265 (58.4%) women self reported eating until full, and 523 (45.6%) men and 785 (36.3%) women self reported eating quickly. For both sexes the highest age adjusted mean values for height, weight, body mass index, and total energy intake were in the eating until full and eating quickly group compared with the not eating until full and not eating quickly group. The multivariable adjusted odds ratio of being overweight for eating until full was 2.00 (95% confidence interval 1.53 to 2.62) for men and 1.92 (1.53 to 2.40) for women and for eating quickly was 1.84 (1.42 to 2.38) for men and 2.09 (1.69 to 2.59) for women. The multivariable odds ratio of being overweight with both eating behaviours compared with neither was 3.13 (2.20 to 4.45) for men and 3.21 (2.41 to 4.29) for women. Conclusion: Eating until full and eating quickly are associated with being overweight in Japanese men and women, and these eating behaviours combined may have a substantial impact on being overweight.

Denney-Wilson, E. and K. J. Campbell (2008). "Eating behaviour and obesity." BMJ 337(oct21_2): a1926-.  [Extract/Full Text]
In the linked study (doi:10.1136/bmj.a2002), Maruyama and colleagues show a significant positive association between two eating behaviours (eating until full and eating quickly) and overweight in a large sample of Japanese adults.1 The study builds on evidence that eating behaviours are important in promoting positive energy balance (taking in more energy than is expended) and may contribute to the current epidemic of obesity. The drive to overconsume energy when it is available is probably an evolutionary imperative; however, until the last decade or so most adults did not have the opportunity to take in enough energy to enable fat to be stored.  The ideal situation whereby our eating behaviours are controlled by biological regulatory systems that tightly regulate appetite and consumption and keep our weight in check-is being challenged. We do not know what drives us to eat quickly or to eat until we are full. Have these drivers changed in parallel with the obesity epidemic and are they modifiable? It may be that the changing sociology of food consumption, with fewer families eating together, more people eating while distracted (for example, while watching television), and people eating "fast food" while on the go all promote eating quickly. Furthermore, the increased availability of relatively inexpensive food, which is more energy dense and served in substantially larger portions, may promote eating beyond satiety. Maruyama and colleagues show that the combination of these two factors-eating quickly and eating until full-are additive (odds ratio for being overweight and having both eating behaviours compared with having neither 3.13 (95% confidence interval 2.20 to 4.45) for men and 3.21 (2.41 to 4.29) for women) ... Given the fundamental importance of preventing overweight, clinicians need to engage with parents. Evidence shows that parents can be supported to make effective changes to their children's eating habits, and that young children can be taught to recognise internal cues and alter consumption accordingly. Clinicians should encourage parents to adopt a child led feeding strategy that acknowledges a child's desire to stop eating that begins from birth. Reassure parents that well children don't starve. Furthermore, because children find it difficult to regulate their energy intake, it is important to inform parents of the environmental stimuli that promote positive energy balance such as serving excessively large meals.  Discussion about replacing energy dense snack foods and drinks with core foods and water, appropriate serving sizes and body weight, what comprises a healthy diet, eating in non-distracting environments, eating together with an adult, and role modelling with slow and relaxed eating is likely to be useful.

Llewellyn, C. H., C. H. M. van Jaarsveld, et al. (2008). "Eating rate is a heritable phenotype related to weight in children." Am J Clin Nutr 88(6): 1560-1566.   [Abstract/Full Text]
Background: There is growing interest in the heritability of behavioral phenotypes related to adiposity. One potential candidate is the speed of eating, although existing evidence for an association with weight is mixed. Objective: We aimed to assess the speed of eating in a sample of 10-12-y-old children to test the hypotheses that higher eating rate is related to greater adiposity and that eating rate is a heritable characteristic. Design: Video data of 254 twin children eating a standard meal at home were used to record eating rate (bites/min) and changes in eating rate across the 4 quarters of the meal. Adiposity was indexed with body mass index SD scores relative to British 1990 norms; for some analyses, children were categorized into groups of overweight or obese and into 2 subgroups of normal-weight (lower normal-weight or higher normal-weight) for comparison of the eating rate within the normal range as well as between clinical and nonclinical groups. All analyses controlled for clustering in twin pairs. Heritability of eating rate was modeled by using standard twin methods. Results: There was a significant linear association across the 3 weight groups for eating rate (P = 0.010), and regression analyses showed that eating rate increased by 0.18 bites/min for each 1-unit increase in body mass index SD score (P = 0.005). The heritability of eating rate was high (0.62; 95% CI: 0.45, 0.74). There was no association between weight group and a change (ie, deceleration) in eating rate over the mealtime. Conclusion: Faster eating appears to be a heritable behavioral phenotype related to higher weight.

Leahy, K. E., L. L. Birch, et al. (2008). "Reducing the energy density of multiple meals decreases the energy intake of preschool-age children." Am J Clin Nutr 88(6): 1459-1468.  [Abstract/Full Text]
Background: The energy density (ED) of an entree affects children's energy intake at a meal consumed ad libitum. However, the effects in children of changing the ED of meals over multiple days are unknown. Objective: We aimed to test the effect of reducing the ED of multiple meals on the ad libitum energy intake of preschool-age children over 2 d. Design: In this crossover study, 3- to 5-y-old children (n = 10 boys, 16 girls) were served manipulated breakfasts, lunches, and afternoon snacks 2 d/wk for 2 wk. Foods and beverages served at these meals during 1 wk were lower in ED than were those served during the other week. ED reductions were achieved by decreasing fat and sugar and by increasing fruit and vegetables. Dinner and an evening snack were sent home with children, but these meals did not vary in ED. The same 2-d menu was served in both conditions. Results: Children consumed a consistent weight of foods and beverages over 2 d in both conditions, and therefore their energy consumption declined by 389 {+/-} 72 kcal (14%) in the lower-ED condition, a significant decrease (P < 0.0001). Differences in energy intake were significant at breakfast on day 1, and they accumulated at manipulated meals over 2 d (P < 0.01). Intake of the nonmanipulated meals was similar between conditions. Conclusions: Children's energy intake is influenced by the ED of foods and beverages served over multiple days. These results strengthen the evidence that reducing the ED of the diet is an effective strategy for moderating children's energy intake.

Baker, J. L., M. Gamborg, et al. (2008). "Breastfeeding reduces postpartum weight retention." Am J Clin Nutr 88(6): 1543-1551.  [Abstract/Full Text] Background: Weight gained during pregnancy and not lost postpartum may contribute to obesity in women of childbearing age.  Objective: We aimed to determine whether breastfeeding reduces postpartum weight retention (PPWR) in a population among which full breastfeeding is common and breastfeeding duration is long.  Design: We selected women from the Danish National Birth Cohort who ever breastfed (>98%), and we conducted the interviews at 6 (n = 36 030) and 18 (n = 26 846) mo postpartum. We used regression analyses to investigate whether breastfeeding (scored to account for duration and intensity) reduced PPWR at 6 and 18 mo after adjustment for maternal prepregnancy body mass index (BMI) and gestational weight gain (GWG).  Results: GWG was positively (P < 0.0001) associated with PPWR at both 6 and 18 mo postpartum. Breastfeeding was negatively associated with PPWR in all women but those in the heaviest category of prepregnancy BMI at 6 (P < 0.0001) and 18 (P < 0.05) mo postpartum. When modeled together with adjustment for possible confounding, these associations were marginally attenuated. We calculated that, if women exclusively breastfed for 6 mo as recommended, PPWR could be eliminated by that time in women with GWG values of 12 kg, and that the possibility of major weight gain (5 kg) could be reduced in all but the heaviest women.  Conclusion: Breastfeeding was associated with lower PPWR in all categories of prepregnancy BMI. These results suggest that, when combined with GWG values of 12 kg, breastfeeding as recommended could eliminate weight retention by 6 mo postpartum in many women.

Shai, I. and M. J. Stampfer (2008). "Weight-loss diets - can you keep it off?" Am J Clin Nutr 88(5): 1185-1186.  [Free Full Text
Standard weight-loss diets provide 500-1000 fewer calories than estimated to be necessary for weight maintenance and initially result in a loss of 0.5-1 kg/wk. Although many people can lose some weight (as much as 10% of initial weight in 6 mo) with such diets, at least part of the weight lost is regained without continued support and follow-up. In recent years it has become increasingly apparent that short-term weight-loss programs, even those that result in dramatic weight loss, are less relevant to long-term health and weight maintenance than is moderate weight loss over a longer duration. Weight maintenance is the main challenge. For example, participants who initially lost 22 kg in a very-low-calorie-diet program had a net loss of 3.3 kg after 3 y of follow-up; only 12% of the participants maintained 75% of their weight loss after leaving the diet program, and 40% gained back more than they had lost. Typically, maximal weight loss occurs in the first 6 mo of therapy, and weight regain begins shortly thereafter. On average, weight loss at 2 y ranges between 3% and 6% for nonpharmacological therapies and between 7% and 8% for pharmacologic therapies. A meta-analysis of 46 trials involving diet advice and counseling estimated a decrease of 0.1 unit of body mass index (in kg/m2) per month from 3 to 12 mo of active intervention and a regain of 0.02 to 0.03 units of body mass index per month subsequently. However, there is some room for optimism. Approximately 60%, 35%, and 19% of the successful weight losers were able to maintain 10% of the weight reduction for 1, 3, and 5 y, respectively. Moreover, if the participants successfully maintained their weight loss for 2-5 y, the chance of longer-term success increased greatly ... The frequency of exercise after the diet program is the strongest predictor of weight loss maintenance, while television viewing is associated with weight gain. Current guidelines to prevent weight gain recommend 60 min per day of at least moderate-intensity physical activity. Clinicians should emphasize to their patients that there are no magic ways to lose weight. A healthy diet should be a life-long strategy. To prevent weight cycling, long-term diet approaches with gradual weight loss should be considered a one-way ticket to good health.  

 

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