You get to hear some pretty interesting conversations when you work in a gym all day. One that comes up time and time again is how exercise affects weight loss. Many believe that if they just exercised more (whether that be cardio, strength training, etc.) they would have their dream body.
But is that the most effective way to lose weight?
When examining a question like this, it’s important to look at what the research says. This will always provide a better answer than one’s own experience. The reason being fitness research looks for general answers, meaning the results apply to the majority of people.
So, what does the research say?
In 2014 a meta-analysis was performed on eight studies examining the effects of exercise-only, diet-only, or combined exercise and diet weight loss protocols on 1,022 participants (1). A meta-analysis basically looks a several research studies on a given topic and finds correlations or differences among them.
Upon the authors review, they found:
1. No significant difference in weight loss between 3-6 months when comparing combined versus diet-only based programs.
2. At 12 months, combined programs produced greater weight loss than diet-only programs.
3. At 3-6 months and 12-18 months, combined programs produced greater weight loss than exercise-only programs.
They concluded that exercise-only weight loss programs aren’t as effective as diet-only or combined programs. Not only that but diet-only and combined protocols produced similar results in the short-term but only combined programs produced better long-term results.
The short answer to our question above is that exercise alone isn’t the most effective way to lose weight. But let’s dig in a little deeper and look at why this is the case.
Weight loss comes down to one basic thing, calories. If you expend more calories than you take in on a daily basis you will lose weight. This is called a caloric deficit.
You can create this deficit via exercise, diet, or both. The main reason why exercise alone isn’t as effective at producing weight loss as diet is because the amount of calories you expend during exercise is relatively small compared to the deficit you can create through food.
For example, a person who weighs 155 lbs. burns roughly 298 calories by running at 5 mph for 30 minutes (2). This would create a deficit of 298 calories. You can create the same deficit by cutting out two sodas per day.
Which of those would be easier to do? Obviously cutting out two sodas. Through food you can create large deficits fairly easily which will produce better results than exercising more and eating the same food.
But, if you notice in the results of the meta-analysis, combined (diet and exercise) programs produced better results in the long run than diet alone. Why is this the case?
In some of the studies, strength training was the main type of exercise performed. Strength training is a crucial component to long-term weight management because it helps you retain and even gain muscle mass, in addition to creating a caloric deficit.
Lifting weights forces your muscles to work harder than normal. This creates the perfect stimulus to hold on to the muscle you currently have and pack on more muscle.
Increased muscle mass improves your metabolism making fat loss easier and more sustainable. It can improve insulin sensitivity, which can help prevent diabetes and obesity. New research also shows the more muscle mass you have, the lower your chance of dying early (3).
Strength training and diet offer somewhat of a 1-2 punch when it comes to weight loss. You create a deficit and retain muscle mass. This helps ensure most of the weight you lose comes from fat.
And that is why combined programs are most effective in the long-run. They offer the exact prescription you need to manage your body composition.
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The debate of exercise or nutrition will undoubtedly go on and on. But the majority of research is clear. Diet is more important for weight loss in the short-term. However, a combined program emphasizing both diet and exercise is best for creating changes that last a lifetime.
References:
1. Johns, D.J. et al. Diet or exercise interventions vs combined behavioral weight management programs: a systematic review and meta-analysis of direct comparisons. J Acad Nutr Diet. 2014 Oct; 114(10): 1557–1568.
2. Harvard Health Publications
3. Srikanthan, P. et al. Muscle mass index as a predictor of longevity in older adults. Am J Med. 2014.
Photo Credit:
1. http://www.illawarramercury.com.au/
