Why More Exercise Doesn't Always = More Calories Burned

🌈 Abstract

The article discusses the "constrained energy model" which suggests that increased physical activity does not necessarily lead to a linear increase in energy expenditure. It explores recent studies that provide further evidence for this model and its implications for weight loss and exercise strategies.

🙋 Q&A

[01] The "Constrained Energy Model"

1. What is the "constrained energy model" and how does it differ from the "additive energy model"?

• The "constrained energy model" suggests that energy expenditure increases with added activity, but only up to a certain point. Beyond that, the body adjusts other processes to maintain total energy expenditure within a narrow range.
• This contrasts with the "additive energy model" which assumes that more exercise = more calories burned.

2. What evidence supports the constrained energy model?

• A 2016 study by Herman Pontzer and colleagues first proposed the constrained energy model.
• Two recent studies have provided additional support:
  • A study by Careau et al. found that energy compensation averaged 28%, meaning a 500 kcal increase in activity only led to a 360 kcal increase in total energy expenditure.
  • Another study found the constrained model held true when participants were in a calorie deficit, while the additive model held true at maintenance or surplus.

3. How does body fat level impact the degree of energy compensation?

• The Careau et al. study found leaner individuals compensated less (29.7%) compared to those with more body fat (45.7%).
• This suggests individuals with greater fat levels may be predisposed to increased adiposity due to stronger energy compensation, or they become stronger compensators as they gain more fat.

[02] Implications for Exercise and Weight Loss

1. Why is "trying to out-train your diet a losing strategy"?

• The amount of exercise required to significantly outpace calorie intake is unrealistic for most people.
• The compensation effect means the actual calories burned during exercise is less than expected, so you can't rely on exercise alone to create a large calorie deficit.

2. How should the goal of training during fat loss be approached?

• The goal should be to maintain muscle and strength, not to burn as many calories as possible through exercise.
• Cardio can be used to increase the calorie deficit, but be mindful not to overdo it and end up in too large a deficit.

3. How does energy balance status impact the degree of compensation?

• At maintenance or surplus, the additive model holds true to a point. But in a deficit, the constrained model applies, and compensation increases.
• This means trying to "speed up" fat loss through excessive exercise is counterproductive, as the compensation effect will kick in.

4. Why should you stop paying attention to your smartwatch's calorie estimates?

• Smartwatches are inaccurate at estimating energy expenditure and can't account for the compensation effect.
• However, they can be useful for tracking step counts to help maintain activity levels during a diet.

5. What are the key benefits of regular exercise beyond just calorie burning?

• Exercise has many health benefits and is important for weight maintenance, not just weight loss.
• The focus should shift from using exercise solely to burn calories, and more towards using it to improve health and support fitness goals.