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Study under review: Dose-response relationship between protein intake and muscle mass increase: a systematic review and meta-analysis of randomized controlled trials
Introduction
Beyond strength and looking good, having more muscle is associated with improved quality of life[1] and reduced all-cause mortality[2], especially in the context of aging. Muscle tissues are also associated with better blood sugar control[3], so low muscle mass is associated with increased risk of type 2 diabetes[4] and age-related physical decline[5].
One way to help maintain or boost muscle is by ensuring adequate protein intake. But how much is “enough,” exactly? Many studies have attempted to answer this question. Based on nitrogen balance studies, your body needs, on average, 0.66 grams of protein per kilogram of bodyweight per day (g/kg BW/d) to not break down muscles and other tissues for amino acids. Based on this data, the recommended intake is at least 0.83 g/kg BW/day. However, a newer technique called the indicator of amino acid oxidation method[6] (IAAO), suggests that this number could significantly underestimate the actual requirements. Older adults may need up to 1.29 g/kg BW/day. For bodybuilders, the requirements [7]could be up to 2.2 g/kg BW/day.
What was studied?
What were the findings?
The bigger picture
Frequently asked questions
What should I know?
Other Articles in Issue #75 (January 2021)
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Safety Spotlight: Women and creatine
The effects of creatine are quite well studied, but its sex-specific safety profile hasn't been. Besides some non-serious side effects, creatine seems safe for women, but more work needs to understand creatine's effects during pregnancy.
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The effects of increased protein intake on overall energy intake in older adults
Boosting protein intake may help stave off the loss of muscle strength and function that can come with age. But does increasing protein affect energy intake in older adults as well? We cover a recent meta-analysis that explored this question.
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Sugar Wars, Episode 6: The Return of the Fructose
How does fructose affect cardiometabolic risk markers calorie-for-calorie compared to glucose or sucrose? This recent meta-analysis aimed to find out.
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Deep Dive: Supplementing for senior strength and size in the context of sarcopenia
This systematic review and meta-analysis explored what supplements can stave off the loss of muscle function that comes with aging. However, the way it categorized the studies it used, along with the overall low quality of those studies, makes its conclusions seem a bit... weak.
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Interview: Cyriac Abby Philips, MBBS, MD, DM (Hepatology)
In this interview, we pick Dr. Philips' brain about the basics of Ayurveda, its safety, and the story behind a recently retracted paper he was involved with detailing a case of acute liver failure and death in a patient who was taking supplements.
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Deep Dive: Comparing the efficacy of diet, exercise, and lifestyle modifications for controlling childhood obesity
This meta-analysis looked at what lifestyle interventions work best for children with overweight and obesity, and how much of a role parental involvement played.
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Deep Dive: Do Low-Carb Diets Stoke the Metabolic Fire?
This meta-analysis concluded that longer-term low-carb dieters feel the metabolic burn, but some methodological concerns may douse this flame a bit.
