SCIENCE FRIDAY: PRESERVING MUSCLE

Beachside protein stand? Taken by PKSenagore July 3, 2017. All rights reserved.

PART II OF A TWO PART SERIES: DIETS AND BODY COMPOSITION
THE INTERNATIONAL SOCIETY OF SPORTS NUTRITION ISSUED A POSITION paper on this topic in June 2017.  The ISSN says it “bases the following position stand on a critical analysis of the literature regarding the effects of diet types (macronutrient composition; eating styles) and their influence on body composition”.  The major diet “archetypes” analyzed by the ISSN include:

• Low and Very Low Energy: total calories are reduced, 800-1800/day
• Low Fat: low percent, < 30%, calories from fat
• Low Carbohydrate (CHO): low percent, < 40%, calories from CHO)
• Ketogenic: very low CHO content; ~ 10%
• High Protein: >25% calories from protein

The complete list of conclusions can be found in the linked article.
 
The Earned Runs summary of the position is as follows:  The desired change in body composition (BC) for ATHLETES is tied to fundamental health parameters, that is, for ALL PEOPLE a higher proportion of lean muscle “reduces the risk of developing metabolic syndrome, bone loss, and multiple complications of sarcopenia” (abnormally decreased muscle mass).  Thus, this lengthy discussion is about the effectiveness of various diets to increase lean muscle mass, mostly at the expense of fat mass (replace fat with muscle).
 
In order to identify whether change has occurred, methods are needed to measure BC. Which one is best? The ISSN says each of the methods investigated, whether simple/inexpensive like measuring skinfold thickness, or complicated/expensive like Magnetic Resonance Imaging (MRI), has “strengths and limitations”.  It would seem best to CHOOSE ONE and continue to use it to measure progress. [Popular diets often use body measurements to show improvements]
 
Which diet is best?  This group of nutrition experts found that MANY types of diets and eating styles can be used effectively to induce these improvements in body composition (BC), with the following cautions:

• If the purpose of a diet is FAT LOSS, calorie restriction will ‘drive’ results. The greater the baseline level of body fat, the greater the restriction can be without the risk of losing lean muscle. In leaner persons, a slower rate of weight loss (less severe restriction) may be needed to preserve muscle mass.

 

• Significantly HIGHER DIETARY PROTEIN intake than is currently recommended may be necessary in RESISTANCE-TRAINED athletes on CALORIE RESTRICTED diets to preserve/maintain lean muscle. Very high amounts may have even greater benefits in these athletes.

 

• Intermittent FASTING does NOT seem to show significant advantages over regular daily calorie restriction in changing BC.

 

• If the purpose of a diet is to GAIN lean muscle weight while resistance training, extra dietary calories can be added. The amount and type of extra calories and the type of training regimen will determine the resulting change in BC.

 
What advice is given to help athletes experience LONG TERM success? The best way to persevere over the long haul is to adopt a diet plan that fits individual needs and allows compliance.
 
Discussion:
ARE YOU DISAPPOINTED? The position paper did not identify a specific magic formula that would help replace fat with muscle in every person. The most important bit of ISSN guidance? The position paper repeatedly stressed that athletes (and all people interested in achieving optimum health) should take care NOT TO LOSE MUSCLE when training hard, or when decreasing calories to lose fat especially if training hard.  Adding protein seems to be the easiest way to avoid muscle loss.
 
The GOOD news is that we can choose the kind of plan that seems to work best for us.  If one doesn’t show results, move on and experiment with others.   The conflicting advice of various trainers, coaches, and nutrition gurus shouldn’t be confusing now. This scientific review of the research shows us that different plans work for different athletes.  The ‘secret sauce’ of any diet + training recipe is to keep protein levels sufficiently high to allow the REPAIR of muscle damaged in workouts plus the BUILDING of new muscle for stronger running.
 
If you’re interested in increasing dietary protein content, go back and read last week’s July 7, 2017 SCIENCE FRIDAY blog post, Part I of this two part series. If not an athlete, you may want to make some changes to insure overall good health.
 
RUN HAPPY!
 
“International Society of Sports Nutrition Position Stand: Diets and Body Composition”
https://www.ncbi.nlm.nih.gov/pubmed/28630601