Aerobic exercise has many health benefits: It keeps the heart's structure youthful, it increases mitochondria, and it reduces our long-term risk of cognitive decline and other neurodegenerative conditions. That's just to name a few.

Exercise is also promoted widely as a strategy for weight loss—often in combination with dietary changes—as it increases total daily energy expenditure and creates an energy deficit.

While 150 minutes per week of moderate-intensity exercise is recommended for general health, higher doses (200–300 minutes per week) are typically required to achieve significant weight loss in individuals with overweight or obesity. However, the weight loss achieved through exercise alone, even at higher doses, is often less than expected. Why? This discrepancy is due to several interrelated mechanisms involving dietary intake, behavioral adaptations, and physiological compensation.^[1]

• Increased appetite: Exercise frequently stimulates appetite, leading to increased food consumption that offsets the calorie deficit created by physical activity. It's hard to burn 500 calories through exercise but easy to eat 500 calories (or more) in a few minutes. Even under highly controlled conditions where adherence to exercise is ensured, studies demonstrate that individuals often increase their energy intake in response to exercise, reducing the net energy deficit.

• Reduced non-essential activity: People may unconsciously reduce their non-exercise physical activity (e.g., walking, standing, and fidgeting) as a way of conserving energy after engaging in structured exercise. These reductions in other components of daily movement can significantly limit the overall increase in daily energy expenditure.

• Constrained energy expenditure hypothesis: According to the constrained total energy expenditure model, the body may adapt to sustained increases in physical activity by reducing energy spent on other processes, such as resting metabolic rate or non-essential activities. This plateau effect limits the total contribution of exercise to daily energy expenditure, particularly over longer durations or higher doses of physical activity. According to this model, someone who has a baseline daily energy expenditure of 2,000 calories per day and adds 200 calories worth of exercise daily would still only expend 2,000 calories per day—not the 2,200 that would be expected.

This all begs the question: Can exercise cause significant weight loss and improvements in cardiometabolic health if the dose is right? And if so, what's the miniumum—and the maximum—dose? How might exercise intensity play a role?

Move it to lose it

"Although discussions surrounding weight loss often fixate on diet to the point of eclipsing exercise altogether, this study’s findings underscore how increasing the ‘dose’ of aerobic activity drives clinically meaningful, highly predictable losses in body weight."- Dr. Rhonda Patrick Click To Tweet

In a recent meta-analysis, researchers compiled the results of 116 weight loss studies including more than 6,800 participants who had overweight or obesity. They only considered studies that were 8 weeks or longer and that used aerobic exercise training interventions like walking or running—both those with and without a calorie restriction co-intervention.^[2]

While the primary focus of the study was on the dose (i.e., weekly duration) of exercise needed for weight loss, exercise intensity was also investigated as a variable that might influence the results. Exercise intensity was categorized as light, moderate, moderate to vigorous, and vigorous.

Any dose of activity leads to weight loss

"While these are all beneficial changes, not all of them reached a level of"clinically significant"at 30 minutes or even 100 minutes per week of exercise. It required a bit more movement for these numbers to change in a meaningful way."- Dr. Rhonda Patrick Click To Tweet

For every 30 minutes of aerobic exercise performed each week:

• body weight dropped by 0.52 kilograms or just over 1 pound.
• waist circumference dropped by 0.56 centimeters.
• body fat percentage declined by 0.37%.
• body fat mass was reduced by 0.2 kilograms or 0.44 pounds.
• subcutaneous and visceral adipose tissue levels declined.

While these are all beneficial changes, not all of them reached a level of "clinically significant" at 30 minutes or even 100 minutes per week of exercise. It required a bit more movement for these numbers to change in a meaningful way.

More exercise means more benefits

"At least 150 minutes per week was required to elicit clinically significant improvements in body fat percentage and waist circumference."- Dr. Rhonda Patrick Click To Tweet

All the way up to 300 minutes per week, aerobic exercise was associated with clinically significant weight loss.

Performing 150 minutes of exercise per week reduced body weight by nearly 3 kilograms or 6 pounds. But performing twice this amount led to more weight loss—just over 4 kilograms or around 9 pounds on average.

At least 150 minutes per week was required to elicit clinically significant improvements in body fat percentage and waist circumference.

Furthermore, while a higher dose of exercise (i.e., 300 minutes per week) was best for improving waist circumference, that same wasn't true for body fat percentage, which was reduced the most (2.1%) at 150 minutes per week, and body fat mass, which was reduced the most (2 kg or 4.4 lb) at 100 minutes per week of exercise.

Intensity matters

"This suggests that high-intensity interval training, which has a broad range of benefits for aerobic fitness and brain health, may also be ideal for improving body composition."- Dr. Rhonda Patrick Click To Tweet

For weight loss, moderate-, moderate-to-vigorous, and vigorous-intensity exercise led to comparable degrees of weight loss regardless of exercise duration.

However, the greatest improvement in body composition—including waist circumference, body fat percentage, and visceral adipose tissue—were observed with more vigorous exercise intensities.

This suggests that high-intensity interval training, which has a broad range of benefits for aerobic fitness and brain health, may also be ideal for improving body composition.

Exercise protocols for weight loss

Here are a few protocols from the studies included in the meta-analysis. These might help inform your own training strategy—whether for weight loss or general fitness goals.

Progressive moderate-intensity exercise: Increase the dose of aerobic exercise, including brisk walking and stationary cycling, for 12 weeks building up to a total of 150–225 minutes per week.

• Month 1: 3 sessions/week for 15 minutes/session at 50-85% heart rate reserve (maximal heart rate minus resting heart rate).
• Month 2: 4 sessions/week for 20-30 minutes/session.
• Month 3: 5 sessions/week for 30-45 minutes/session.

High-intensity interval training: Perform 4 bouts of 4-minute interval treadmill running at 85–95% of peak heart rate interspersed by 3-minute walking at 50–60% of peak heart rate and a 7-minute rest a total of 4 times per week for a total of 6 weeks.

• Weeks 1–2: Interval intensity is 85% of peak heart rate.
• Weeks 3–4: Increase the interval intensity to 90% of peak heart rate.
• Weeks 5–6: Increase the interval intensity to 95% of peak heart rate.

Steady-state aerobic exercise: Endurance activities, including aerobics, circuit training, jogging, and fast walking, for 1 year with a total of 180 minutes of exercise weekly.

• Frequency: 3 sessions/week.
• Intensity: 60-80% of maximal heart rate.
• Duration: 60 minutes/session.

Each of these protocols should begin with a 10-minute warmup and a 5-minute cooldown. Change the number of training sessions per week based on personal preference, exercise tolerance, and training goals.