Exercise Versus Diet For Losing Weight

 

Picture of visceral fat from FitTrack

My colleagues and friends think that eating less (calorie restriction) or dieting is much more effective compared to exercise for losing visceral fat (fat stored deep inside our belly, wrapping our liver, intestines and other organs). Subcutaneous fat is fat that is stored underneath our skin.

Visceral fat makes up about one tenth of all the fat stored in our bodies. Visceral fat represents a much bigger metabolic risk than subcutaneous fat and can lead to cardiovascular disease, Type II diabetes metabolic syndrome, cancer and other chronic diseases.

Previous obesity management guidelines recommend the use of exercise and calorie restriction for weight loss. exercise causes fat loss via an increase in energy intake. Calorie restriction (or dieting) results in fat loss via a decrease in energy intake.  Both interventions achieve fat loss via a negative energy balance.

This systematic review used a weekly caloric deficit to control for the overall effects of the 2 interventions. Data from 40 studies involving 2190 individuals were analyzed. 

While both exercise and calorie restriction (dieting) effectively reduced viseral fat, only exercise showed increasing amounts of exercise result in greater visceral fat loss.

The effect of calorie restriction was not dose dependent, meaning that greater calorie deficits do not translate to greater visceral fat loss. You can eat less, but that does not mean you lose more visceral fat.

The authors found that increasing amounts of exercise translate into greater reductions in visceral fat in people who are overweight and obese compared to just eating less. 

A substantial loss of body weight by dieting will also result in a loss muscle mass and this will subsequently decrease basal metabolic rate. A lower metabolic rate would require a further reduction in calories for weight loss and this cannot be continued. Exercising to lose weight may be achievable while preserving or even gaining muscle mass (leading to increase in basal metabolic rate).

The authors conclude that exercise is more effective than dieting for metabolic health improvements, and supports its use for reducing visceral fat in people who are overweight and obese.

Of course it will be quicker and more effective if you eat less and exercise at the same time. But it has to be sustainable, otherwise you cannot keep it up.

Reference

Recchia F, Leung CK, Yu AP et al (2023). Dose-response Effects Of Exercise And Caloric Restriction On Visceral Adiposity In Overweight And Obese Adults: A Systematic Review And Meta-analysis On Randomised Controlled Trials. BJSM. DOI: 10.1136/bjsports-2022-106304.