• Cleo Protogerou

Does aerobic exercise alone result in noteworthy weight loss? In a word: No

Updated: Apr 18, 2018

The Evidence:

Thorogood, A., Mottillo, S., Shimony, A., Filion, K. B., Joseph, L., Genest, J., ... & Eisenberg, M. J. (2011). Isolated aerobic exercise and weight loss: A systematic review and meta-analysis of randomized controlled trials. The American Journal of Medicine, 124, 747-755. doi:10.1016/j.amjmed.2011.02.037

What did the meta-analysis look into?

This meta-analysis investigated whether an isolated aerobic exercise programme of at least 2 hours per week can result in noteworthy weight loss. Isolated exercise programmes measure the effects of exercise alone – without dieting. The intensity of exercise programmes reviewed was moderate (raised heart rate up to 40 to 80 percent higher than when sitting) and included walking, jogging, cycling & rowing machines, aerobic routines, and mini-trampoline. The meta-analysis synthesized evidence from 14 experimental studies, including 1847 overweight and obese adults from Europe, North America, Japan, and Brazil. The weight loss of those who were on the 2-hour weekly exercise programme was compared to that of overweight & obese adults that did not follow any scheduled aerobic exercise.

In addition to weight loss, the meta-analysis also measured the effects of the 2-hour exercise programme on fat, blood pressure, cholesterol, and triglyceride levels.

What did the evidence suggest for weight loss and related outcomes?

In general, those who exercised lost more weight than those who did not, but the weight loss was negligible. Specifically, the 6-month exercise programmes resulted in losing 1.6 kilos, reducing the waistline by 2.12 cm, and in small reductions in total cholesterol and blood pressure. The 12-month exercise programmes resulted in losing 1.7 kilos and reducing the waistline by 1.95 centimetres. There were not enough studies to synthesize evidence for other outcomes, at 12 months.

The take-home message

Obese and overweight people that engage in exercise programmes of moderate intensity may experience weight loss (up to 1.7 kilos) and waistline reduction (up to 1.95 centimetres), assuming that the exercise is maintained for at least 2 hours per week, and over the period of a year. This type of exercise may also result in small improvements in cholesterol and blood pressure. However, these outcomes are too small to justify recommending stand-alone exercise programmes. Broadly speaking, exercise alone appears to be an ineffective weight loss strategy for obese and overweight people.