Diet, Exercise, or Both?

Diet and exercise. While these are often paired together, which is more important? Are both necessary?

Recent studies have shown that energy restriction through diet results in similar weight loss to diet plus exercise, while exercise alone results in lesser weight loss (1, 2). For many people skimming over these results in their doctor’s office magazine, dieting might seem like the path to take. But they’re only seeing half the story.


While individuals who lose weight through dieting may be shedding the desired pounds, they’re not just losing fat mass, but lean muscle mass as well. Lean muscle mass includes all types of muscle throughout your body. This muscle keeps your heart pumping, keeps your brain working, and helps you perform all your day-to-day activities.

Combining exercise with diet will help you keep your lean muscle mass while losing fat mass – a win-win situation (1-4)! To top that, exercise will not only help you keep your lean muscle mass, but it will improve it – leading to greater muscular strength and endurance (4).


In addition to saving your muscle mass, exercising along with energy restriction leads to improved cardiovascular function. Exercising increases individuals’ abilities to exercise at a higher capacity (4), improves blood vessel function, and keeps the lungs and heart working more efficiently (3).   


Including exercise in your weight loss program is also essential for maintaining proper insulin sensitivity. Exercise in addition to energy restriction improves insulin sensitivity greater in the long-term compared to diet modification alone (1). Aerobic and resistance training can be used to improve insulin sensitivity (3).


Besides the health benefits above, adding exercise to any weight loss program can increase the body’s efficiency at burning calories. As individuals exercise, their fitness levels increase. This means that they can perform more work at a given heart rate than someone who is less fit. And the more you work, the more calories you will expend.

Exercise also raises an individual’s resting metabolic rate. The resting metabolic rate is the amount of energy required to keep your body functioning at rest. This energy requirement decreases with prolonged calorie restriction. Adding exercise to diet modification helps reverse this decrease in resting metabolic rate and keeps your body burning more calories at rest (5).


So don’t let that magazine article trick you into thinking that weight loss is the only thing you should be worrying about. Your body is a complex combination of many different organs and functions, and you have to keep them all happy. Combining exercise with healthy diet modification will not only help you achieve your weight goals but will also promote greater lean body mass, improved cardiovascular function, increased insulin sensitivity, and enhanced calorie-burning efficiency.


to learn more about your body!

1.     Bouchonville, M., Armamento-Villareal, R., Shah, K., Napoli, N., Sinacore, D. R., Qualls, C., & Villareal, D. T. (2014). Weight loss, exercise or both and cardiometabolic risk factors in obese older adults: results of a randomized controlled trial. International journal of obesity38(3), 423-431.

2.     Amorim Adegboye, A. R., & Linne, Y. M. (2013). Diet or exercise, or both, for weight reduction in women after childbirth. The Cochrane Library.

3.     Colberg, S. R., Sigal, R. J., Yardley, J. E., Riddell, M. C., Dunstan, D. W., Dempsey, P. C., ... & Tate, D. F. (2016). Physical activity/exercise and diabetes: a Position Statement of the American Diabetes Association. Diabetes Care39(11), 2065-2079.

4.     Miller, C. T., Fraser, S. F., Levinger, I., Straznicky, N. E., Dixon, J. B., Reynolds, J., & Selig, S. E. (2013). The effects of exercise training in addition to energy restriction on functional capacities and body composition in obese adults during weight loss: a systematic review. PLoS One8(11), e81692.

5.     Heyward, V. H. (2010). Advanced fitness assessment and exercise prescription 6th edition. Human kinetics.