NutritionHow Body Composition Affects Weight Loss

How body composition with increased Lean Body Mass affects weight loss, maintenance, and health.  Why Protein consumption is so important and why we stress it

“On average, a 5-pound increase in muscle mass can raise your basal metabolic rate (BMR) by about 30 to 50 extra calories per day.”

Here’s why:

  • Each pound of muscle burns around 6 to 10 calories per day at rest, depending on individual factors.
  • So 5 pounds of new muscle would burn roughly 30 to 50 more calories per day, even without extra activity.

It’s not a huge number by itself, but over time it adds up—plus, more muscle improves strength, body composition, and how efficiently you burn calories during activity.

Losing 20 pounds typically causes a decrease in basal metabolic rate (BMR) of about 300 to 400 calories per day, on average.

Here’s why:

  • For every pound of body weight lost, your body generally burns about 10 to 20 fewer calories per day at rest.
  • So 20 pounds lost × 15–20 calories per pound = 300–400 fewer calories burned daily.

This drop happens because:

  • Your body becomes smaller and needs less energy to maintain itself.
  • The body may also try to conserve energy after weight loss (called adaptive thermogenesis).

That’s why, after losing weight, it’s important to maintain muscle through resistance training and eat enough protein to help keep your metabolism higher.

Here are some well-known studies that show higher protein intake and resistance training help preserve muscle mass during weight loss:

1. Pasiakos et al. (2013)

Title: Higher-protein diets and preservation of lean mass during weight loss in overweight and obese adults: a meta-analysis

  • Summary: This meta-analysis reviewed 24 studies and found that higher protein intake significantly preserved lean muscle mass during weight loss compared to standard protein diets.
  • Takeaway: Protein-rich diets help prevent muscle loss while reducing fat.

2. Longland et al. (2016)

Title: Higher compared with lower protein intake during an energy deficit combined with intense exercise promotes greater fat loss and preservation of lean mass

  • What they did: Young men followed a calorie deficit and resistance training program. One group had high protein (~2.4g/kg body weight); the other had lower protein (~1.2g/kg).
  • Result: Both groups lost weight, but the high-protein group lost more fat and preserved more muscle.
  • Link: PubMed Study

3. Layman et al. (2005)

Title: Dietary protein and exercise have additive effects on body composition during weight loss in adult women

  • Summary: Middle-aged women on a higher-protein diet with resistance training lost more fat and maintained more muscle mass compared to those on a traditional high-carb diet.
  • Conclusion: Protein plus exercise works better for preserving muscle.

4. Campbell et al. (1999)

Title: The effects of resistance training and dietary protein intake on muscle mass and strength in older adults

  • Finding: Older adults who consumed more protein and did resistance training showed increased muscle strength and better muscle preservation during weight loss.
  • Importance: This supports protein + training even in older populations.

Bottom line:

A higher-protein diet (around 1.6–2.4 g/kg of body weight) combined with resistance training significantly helps preserve lean muscle mass and promote fat loss during a calorie deficit. This strategy is backed by multiple studies across age groups and fitness levels.

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