New studies by McMaster University researchers have confirmed that people of all ages find it difficult to prevent weight gain; and it is terrifically difficult to get rid of it later and to keep it off once lost.
Lead author Leslea Peirson said, "This is an important area to investigate, as we know that overweight and obesity are public health problems impacting a growing proportion of the Canadian population, and that this is related to many health problems."
The reports reviewed studies about the prevention and treatment of overweight and obesity among children and adults and about keeping lost weight off.
- Regarding prevention of overweight/obesity among children and youth, a review of 90 studies found that the programs that work best were delivered in educational settings, and included both diet and exercise and lasted 12 weeks to a year.
- Regarding treating overweight/obesity among children and youth, a review of 31 studies found that enrollment in a program that focuses on changes in diet, exercise and lifestyle can help reduce weight and, more importantly, enrollment in such a program also improves health and quality of life in children and adolescents. However, the permanence of this weight loss has yet to be studied.
- Regarding prevention of overweight/obesity among adults, a search of more than two decades of research literature found that almost no trials have been conducted to investigate programs that help normal-weight adults maintain their normal weight. A single small study conducted in the US in the 1980s showed benefits from a 12-month education and incentive-based program.
- Regarding treating overweight/obesity among adults, a review of 68 studies found that doing some activity is better than doing nothing. Adults who took part in some form of treatment had, on average, a 3 kilogram (or 7 pound) greater weight loss than adults who did not. Weight loss results did not differ whether treatments involved diet, exercise, lifestyle changes or drugs (orlistat or metformin). However, the drugs had side effects that the other strategies did not.
- Regarding keeping the weight off once lost, a review of eight studies since 2011 found that doing something to keep that weight off, either through diet, exercise, lifestyle changes or even drugs, can help, at least in the short term. There were no studies addressing the long-term sustainability of weight maintenance strategies. Use of drugs along with behavioral changes may help maintain a loss of 5 percent body weight, but this combined strategy did not make a difference in maintaining a loss of 10 percent of body weight.
Peirson said, "We know that more research is needed that looks at programs designed to prevent weight gain in normal weight adults, youth and children. Future research should look at the longevity of weight loss and study the health consequences of repeated cycling of weight loss and gain."
The study is published in CMAJ Open.