To lose weight, you need to burn more calories than you consume.
Exercise can help you achieve this by burning off some extra calories.
However, some people claim that exercise isn't effective for weight loss on its own.
This may be because exercise increases hunger in some people, making them eat more calories than they burned during the workout.
Is exercise really helpful for weight loss? This article takes a look at the evidence.
Exercise is really great for your health (1).
In fact, people who work out on a regular basis are thought to have up to a 50% lower risk of dying from many of these illnesses (11).
Exercise is also incredibly good for your mental health, and it can help you manage stress and unwind (12).
Keep this in mind when you consider the effects of exercise. Even if it isn't effective for weight loss, it still has other benefits that are just as important (if not more).
Bottom Line: Exercise is about way more than just weight loss. It has various powerful benefits for your body and brain.
Exercise is often advised for weight loss, but people should really aim for fat loss (13).
In fact, it's been estimated that when people lose weight, about a quarter of the weight they lose is muscle (15).
When you cut back on calories, your body is forced to find other sources of fuel. Unfortunately, this means burning muscle protein along with your fat stores (16).
This is also important because muscle is more metabolically active than fat.
Preventing muscle loss can help counter the drop in metabolic rate that occurs when you lose weight, which makes it harder to lose weight and keep it off (13).
Additionally, most of the benefits of exercise seem to come from improvements in body composition, overall fitness and metabolic health, not just weight loss (20).
Even if you don't lose "weight," you may still be losing fat and building muscle instead.
For this reason, it can be helpful to measure your waist size and body fat percentage from time to time. The scale doesn't tell the whole story.
Bottom Line: When you lose weight, you want to maximize fat loss while minimizing muscle loss. It is possible to lose body fat without losing much weight on the scale.
One of the most popular types of exercise for weight loss is aerobic exercise, also known as cardio. Examples include walking, running, cycling and swimming.
Aerobic exercise doesn't have a major effect on your muscle mass, at least not compared to weight lifting. However, it is very effective at burning calories.
A recent 10-month study examined how cardio affected 141 obese or overweight people. They were split into three groups and not told to reduce calorie intake (21):
- Group 1: Burn 400 calories doing cardio, 5 days a week
- Group 2: Burn 600 calories doing cardio, 5 days a week
- Group 3: No exercise
Group 1 participants lost 4.3% of their body weight, while those in group 2 lost a little more at 5.7%. The control group, which didn't exercise, actually gained 0.5%.
Therefore, adding cardio to your lifestyle is likely to help you manage your weight and improve your metabolic health. Just don't compensate for the exercise by eating more calories instead.
Bottom Line: Doing aerobic exercise regularly can increase the number of calories you burn and help you lose body fat.
All physical activity can help you burn calories.
However, resistance training — such as weight lifting — has benefits that go beyond that.
Resistance training helps increase the strength, tone and amount of muscle you have.
This is important for long-term health, since inactive adults lose between 3–8% of their muscle mass per decade (24).
This also helps prevent the drop in metabolism that can occur alongside weight loss.
One study of 48 overweight women on a very-low-calorie diet found that those who followed a weight lifting program maintained their muscle mass, metabolic rate and strength, even though they lost weight (28).
Women who didn't lift weights lost weight too, but they also lost more muscle mass and experienced a drop in metabolism (28).
Because of this, doing some form of resistance training is really a crucial addition to an effective long-term weight loss plan. It makes it easier to keep the weight off, which is actually much harder than losing it in the first place.
Bottom Line: Lifting weights helps maintain and build muscle, and it helps prevent your metabolism from slowing down when you lose fat.
One of the main problems with exercise and weight loss is that exercise doesn't just affect the "calories out" side of the energy balance equation.
It can also affect appetite and hunger levels, which may cause you to eat more calories.
Exercise May Increase Hunger Levels
One of the main complaints about exercise is that it can make you hungry and cause you to eat more.
It's also been suggested that exercise may make you overestimate the number of calories you've burned and "reward" yourself with food. This can prevent weight loss and even lead to weight gain (29, 30).
Exercise May Affect Appetite-Regulating Hormones
Physical activity may influence the hormone ghrelin. Ghrelin is also known as "the hunger hormone" because of the way it drives your appetite.
Interestingly, studies show that appetite is suppressed after intense exercise. This is known as "exercise anorexia" and seems tied to a decrease in ghrelin.
However, ghrelin levels go back to normal after around half an hour.
So although there is a link between appetite and ghrelin, it doesn't seem to influence how much you actually eat (34).
Effects on Appetite May Vary by Individual
Bottom Line: How exercise affects appetite and food intake varies between individuals. Some people may become more hungry and eat more, which can prevent weight loss.
The effects of exercise on weight loss or gain varies from person to person (43).
Although most people who exercise will lose weight over the long term, some people find that their weight remains stable and a few people will even gain weight (44).
However, some of those who gain weight are actually gaining muscle, not fat.
However, the most effective strategy involves both diet and exercise (47).
Bottom Line: The body's response to exercise varies between individuals. Some people lose weight, others maintain their weight and a few people may even gain weight.
Keeping weight off once you have lost it is hard.
In fact, some studies show that 85% of people who go on a weight loss diet are unable to keep the weight off (48).
Interestingly, studies have been done on people who have lost a lot of weight and kept it off for years. These people tend to exercise a lot, up to an hour per day (49).
It's best to find a type of physical activity you enjoy and that fits easily into your lifestyle. This way, you have a better chance of keeping it up.
Bottom Line: People who have successfully lost weight and kept it off tend to exercise a lot, up to an hour per day.