Preserving Healthy Muscle During Weight Loss
If you feel like getting into the nitty gritty details: here’s the link to the research paper where I got this information: https://pmc.ncbi.nlm.nih.gov/articles/PMC5421125/ I read through and wrote some bullet points of the important facts I wanted to share!
KEY TAKEAWAYS:
Rapid weight loss is associated with muscle loss.
When humans lose weight, they typically lose muscle.
Muscle loss could increase risk of developing sarcopenia - abnormally low muscle mass & impaired muscle function
Current data shows the following:
1. Compared with a people who are normal weight, those with obesity have more muscle mass BUT poor muscle quality
2. Diet-induced weight loss reduces muscle mass without adversely affecting muscle strength
3. Weight loss improves physical function.
4. A high-protein intake helps preserve lean body mass during weight loss but does not improve muscle strength and could have adverse effects on metabolic function.
5. Both endurance and resistance exercise helps to preserve muscle mass during weight loss.
Weight loss and weight gain are accompanied by corresponding changes in both body fat and muscle mass.
Studies consistently show that obesity is associated with poor muscle quality which affects physical function.
One study found that older adults with obesity had ~20% more thigh muscle mass and 2x more muscle lipid content than older adults with normal weight.
Reduced muscle strength and power are key predictors of serious adverse outcomes (inability to participate in daily life activities, falls, disability, fractures…)
20-30% of weight loss is muscle mass when losing through diet alone.
Regular resistance training paired with a high-protein diet are recommended for persons with obesity who undergo weight loss therapy to limit the loss of muscle mass.
Dietary amino acids, insulin, and contractile activity are the major regulators of muscle protein synthesis and breakdown.
Exercise improves insulin sensitivity and stimulates muscle protein synthesis.
One study on both men & women with obesity found that a low-calorie diet combined with 300 minutes/week of moderate-intensity aerobic exercise decreases thigh muscle BUT the exercise group loses 50% less.
2 studies found that daily brisk walking for approximately 1 hour (or 60-minutes of other vigorous activity) preserved muscle mass.
Inadequate protein intake results in loss of muscle mass.
As important as total daily protein intake is, the distribution of protein intake over the course of the day matters, too.
There’s a refractory period during which muscle protein synthesis, once stimulated by amino acids, cannot be stimulated again (muscle-full phenomenon.)
2 studies reported greater overall muscle protein synthesis rate throughout the day when protein intake was evenly distributed throughout the day rather than skewed (example: most of your protein at dinner)
Weight loss, despite causing loss of muscle mass, has beneficial effects on muscle quality and improves overall physical function!
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