If you’re trying to lose weight, you may be wondering how much you should be exercising and what types of exercise you should be doing.

At its simplest, losing weight means burning more calories than you consume. So, it makes sense to include exercise in your routine, since it helps you burn more calories.

However, vigorous exercise can also help you work up an appetite. This may cause confusion about the role of exercise in weight loss and whether it can help.

So, what exactly is the purpose of exercise if you’re trying to lose weight? This article takes a look at the evidence to help you find the answer and figure out what’s best for you.

Share on Pinterest
Guille Faingold/Stocksy United

One of the most popular types of exercise for weight loss is aerobic exercise, also known as cardio. Examples include:

  • walking
  • running
  • cycling
  • swimming

Aerobic exercise doesn’t have a major effect on your muscle mass, at least not compared to lifting weights. However, it is very effective at burning calories.

A 10-month study examined how cardio without dieting affected 141 people with obesity or overweight. Participants were split into three groups and not told to reduce calorie intake (1).

Those who burned 400 calories per cardio session (5 times per week) lost 4.3% of their body weight, while those who burned 600 calories per session (also 5 times per week) lost a little more, at 5.7%. The control group, which didn’t exercise, actually gained 0.5% of their body weight.

Other studies also show that cardio can help you burn fat, especially the dangerous belly fat that increases your risk of type 2 diabetes and heart disease (2, 3, 4).

That means adding cardio to your lifestyle is likely to help you manage your weight and improve your metabolic health, if you keep your caloric intake the same.

Summary

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.

One study of 141 older adults with obesity examined the effects of cardio, resistance training, or both on body composition during a period of intentional weight loss. This study found that those who did no exercise or cardio alone lost fat but also lost more muscle and bone mass than the groups that did resistance training (5).

So, resistance training appears to have a protective effect on both muscle and bone during periods of reduced calorie intake.

Higher amounts of muscle also increase your metabolism, helping you burn more calories around the clock — even at rest. This is because muscle is more metabolically active than fat, meaning it requires more energy (6).

This also helps prevent the drop in metabolism that can occur alongside weight loss.

Because of this, doing some form of resistance training is 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.

Summary

Lifting weights helps maintain and build muscle, and it helps prevent your metabolism from slowing down when you lose fat.

High intensity interval training (HIIT) is a type of exercise characterized by short bursts of intense exercise followed by a brief rest before repeating this cycle. HIIT can be done with cardio or resistance training exercises and provides the benefits of both (7).

Most HIIT workouts are only 10–20 minutes long, but they offer some powerful benefits in regard to weight loss.

One 2017 review of 13 high quality studies found that HIIT and cardio exercise provided similar benefits — namely, reduced body fat and waist circumference — for people with overweight and obesity.

However, HIIT exercise achieved these same benefits with a 40% time savings compared to cardio (8).

Because of the intensity of HIIT, you should consult a healthcare professional before starting a new HIIT routine, especially if you have known heart concerns.

Summary

HIIT may offer similar benefits as cardio exercise, with about half of the time commitment.

You’ve probably heard that physical exertion is a good way to work up an appetite, or maybe you even found yourself eating more than usual after a vigorous workout.

However, most research points to exercise having an appetite suppression effect.

One study in 20 active, healthy adults noted that they ate more food in the meal prior to a workout than after — and actually found that, overall, participants ate less food on the days they exercised than the days they didn’t (9).

In another study in 26 women with obesity on low calorie diets, researchers found that short HIIT sessions had a strong appetite suppressing effect (10).

Researchers have also noted that morning exercise appears to be more beneficial for energy balance and calorie intake than evening exercise — further supporting the theory that exercise can reduce appetite (11).

Regardless, more research is needed, and hunger responses to exercise are likely highly individual. If you’re trying to lose weight but tend to eat more than usual after vigorous or long exercise sessions, consider shorter durations (like HIIT) or less intense exercise.

Summary

Exercise may make you more or less hungry; however, research mostly points to exercise having an appetite reducing effect.

Exercise is really great for your health in many ways, not just in terms of weight management (12).

Regular exercise can improve your blood sugar control and may help reduce your risk of chronic diseases like heart disease, type 2 diabetes, and certain cancers (13, 14).

Exercise also helps you to maintain and grow your muscle mass, keep your bones strong and dense, and prevent the onset of conditions like osteoporosis — which is characterized by bone brittleness (15, 16).

Additionally, exercise offers some mental benefits. It can help you reduce your stress levels and manage stress more effectively, and it appears to offer some protection against neurodegenerative conditions like Alzheimer’s disease (17, 18).

Keep these benefits in mind when you consider the effects of exercise. Even if it doesn’t make a huge difference for weight loss, it still has other benefits that are just as (if not more) important.

Summary

Exercise is about way more than just weight loss. It has various powerful benefits for your body and brain.

Because of its numerous health benefits, exercise should absolutely be a part of your routine — regardless of your weight goals. In fact, most successful weight loss maintainers listed in the National Weight Control Registry, who have lost at least 30 pounds (14 kg) and kept it off for at least 1 year, report exercising for at least 1 hour per day (19).

The Physical Activity Guidelines for Americans outline ideal exercise amounts for all ages to help optimize health. For adults, they are (20):

  • Aerobic (cardio) exercise: 150–300 moderate intensity minutes or 75–150 vigorous intensity minutes per week
  • Muscle-strengthening (resistance) exercise: 2 or more days per week of exercises utilizing all major muscle groups

However, if your goal is weight loss, you should prioritize diet over exercise because it will have a much larger impact. If your time is limited, consider resistance training (rather than cardio) to help maintain your muscle mass and metabolic rate or HIIT to help you achieve a similar calorie burn as cardio in less time (21).

Additionally, don’t depend just on the scale to track your progress. If you are gaining muscle while losing fat, your weight may not change as quickly as you’d like it to — however, you’ll be healthier for it. Consider taking your measurements as well, and keep track of how your clothes fit. These are much better indicators of fat loss than weight alone.

Summary

Whether you’re trying to lose weight or not, aim for at least 150 minutes of moderate intensity exercise and 2 resistance training sessions per week for optimal health.

Exercise is important for overall health, and different types of exercise may offer different advantages when it comes to weight loss.

If you’re trying to lose weight, you may particularly interested in resistance training, which can preserve your fat-free mass and increase your calories burned at rest, and HIIT, which provides the same benefits as cardio, but for less time.

But remember, with a goal of sustainable weight loss, it’s also really important to follow a modestly calorie restricted diet comprised mostly of whole foods.