What to do: diet, exercise or both?

What to do: diet, exercise or both?

Johns DJ, Hartmann-Boyce J, Jebb SA, Aveyard P; Behavioural weight Group Management Review.

Weight loss can reduce the health risks associated with excess weight or obesity. However, the most effective method of losing weight remains unclear. Some programs emphasize physical activity, others diet, but the existing evidence are often contradictory.

A study examined the clinical efficacy of combined weight maintenance programs (BWMPs) and programs with a single intervention in losing weight, by using comparisons within the study. That is, exercise only, diet only and exercise combined with diet.

Randomized controlled studies were included among the three groups with at least 12 months of intervention, carried out in adults with overweight and obesity (body mass index ≥25). Systematic research from nine databases were executed and two reviewers extracted data independently.

Random effects meta-analyzes were conducted for the average difference in weight change within 3 to 6 months and 12 to 18 months.

A total of eight studies were included, representing 1,022 participants, most of which were women. The results showed no significant difference in weight loss from baseline or in the 3 to 6 month group among those who did exercise only when compared with the group that made diet only.

However, at 12 months, a significantly greater weight loss was detected in the group that combined exercise and diet. Weight loss is similar in the short term but in the long-term, weight loss is greater when diet and physical activity are combined.

Programs based on physical activity alone are less effective than programs that combine exercise and diet, both in the short and long term.


Dr. Ivani Manzzo is PhD in Science from the School of Medicine UNIFESP – EPM in São Paulo, Brazil, with emphasis on obesity, pregnancy and exercise. In 2010 she began hers studies as Life Coach and has since worked helping people achieve their nutritional and heath goals. These articles are published with Dra Ivani Manzzo’s permission.