Why you shouldn't exercise for weight loss

Author: Adam Macdougall   Date Posted:25 November 2019 

For most guys looking to lose a few kilos, the most common answer would be to lace up the joggers and get out for a run. And while that's a great response, is it as beneficial as we think? 

We all know the importance of physical activity for a healthy life, but how important is exercise for weight loss? Well, according to science, very little. 

 

Now, before we get into why working out won't help your waistline, exercise is still very, very important. Not just for your physical wellbeing, but also for your mental health.

Keeping active has been proven to have a positive influence on many diseases, with research showing it can reduce your risk of heart disease, type 2 diabetes, Alzheimer's disease, and dementia to name a few. 

Exercise is also important in helping you maintain weight loss once you've achieved a healthy weight range.

What most studies have found, however, is that exercise may play a much smaller role in weight loss than we've been led to believe.

 

Is exercise beneficial for weight loss?

Dozens of studies have looked at the connection between exercise and weight loss, and the results are pretty clear - exercise alone is pretty useless for weight loss. 

meta-analysis of over 40 different studies on exercise and weight loss found that exercise alone leads to only modest weight reductions. This was also found in a 1999 review on exercise interventions for weight loss, showing exercise to have just a small impact on body mass.

A 2003 University of Western Australia study found similar results. In this study, researchers looked at the effects of energy restriction (diet) and vigorous exercise on body composition. Participants were split into different groups and given either light or vigorous exercise programs and similar energy-restricted diets. The study found that weight loss was pretty much the same for both groups, regardless of the exercise intensity. This indicates that an energy-restricted diet is key, but increased exercise provided no additional weight loss. 

 

Why is diet more important than exercise for weight loss?

As I like to say, you can't out-train a bad diet. The average Australian man (5'9" tall, 86kg) will burn 500 calories on an exercise bike in an hour if they rip in. If you were to do this seven days a week, you'd lose half a kilo of fat according to the Wishnovsky rule. This rule says that one pound of fat equals about 3500 calories, so to burn one pound of fat you would need to reduce your weekly calorie intake by 3500 (500 calorie deficit per day).

By exercise alone, it would take you nearly a month of riding an hour on a bike every day to lose 2kg of fat.

For someone trying to lose a lot more than 2kg a month, exercising your weight off is going to take a while. 

While there are many different variables that influence it, weight loss is fundamentally a result of using more energy than you consume. This is the "calories in, calories out" concept. If you eat fewer calories than you burn, this is a calorie deficit and you will lose weight. If you eat more calories than you burn, this is a calorie surplus and you will gain weight.

Exercise and dieting are similar for weight loss in that they both create a calorie deficit, either by restricting energy or using more of it. So while you could exercise for an hour per day to create a calorie deficit, you could alternatively just reduce your calorie intake by 500 calories and lose the same amount of fat. 

Restricting your energy by dieting works better than just using more energy in the form of exercise. When dieting, you're typically more strict on the food you eat, but after exercise studies have shown that people often compensate and eat more than they otherwise would. This was found in a 2012 review that showed people often overestimate how much energy exercise actually burns and compensate by eating more after working out, undoing the weight loss benefits of the exercise.

 

So exercise is completely useless?

Not at all. Exercise is pretty much a magic pill for keeping your body and mind happy and healthy. Exercise is also key for weight maintaining a healthy while watching your calorie intake. But for weight loss itself? Yeah, exercise alone won't help you lose much. 

If you exercise while also following an energy-restricted diet, however, it definitely helps! Just be sure to not compensate for the exercise you do with extra food. Think of exercise as an add on and focus on restricting your energy intake for fat loss.