PROTEIN OR KETONES ESTERS: WHICH IS BEST FOR MUSCLE?

KETONE ESTERS VS HIGH PROTEIN ENERGY-RESTRICTED DIET SUMMARY

• A high protein diet was superior to ketone esters for preserving muscle mass while dieting.

• High protein and ketone esters preserved aerobic capacity while dieting.

• Ketone esters were superior to high protein for preserving metabolic rate while dieting.

• The Ketone ester group had lower stress parameters compared to the other groups.

• Combining exogenous ketones and high protein may be advantageous while dieting.

• Contrary to other studies, the high protein group did not reduce appetite.

Introduction to Ketone Esters

Maintaining lean body mass while reducing body fat percentage is important for any bodybuilder or athlete while dieting. Numbers on the scale don’t mean much if you have lost muscle and have reduced athletic performance. The negative effects of food restriction and reduced calorie intake while dieting includes:

1. Reduced resting metabolic rate

2. Loss of lean muscle mass

3. Increased hunger

4. Reduced exercise performance.

Dieting for prolonged periods can result in metabolic adaptation.  Metabolic adaptations to calorie restriction results in fewer calories burned per day.  Long-term dieting can result in losing body fat and muscle at a 3:1 ratio. (Weinheimer et al., 2010)

While dieting, it is not uncommon to feel sluggish and lethargic. This decrease in energy causes a reduction in daily physical activity resulting in a decrease in total daily energy expenditure. Generally, when on a diet, people may go to the gym. However, other activities may be reduced, such as spending more time sitting down and less time walking around.

Maintaining Muscle Mass While Dieting

Strength training is essential for maintaining muscle mass. A reduced number of calories can result in decreased muscle protein synthesis and an increase in muscle tissue breakdown. (Carbone et al., 2013; Pasiakos et al., 2010) A high-protein diet has been shown to preserve muscle mass while dieting. (Tinsley et al., 2019)

Ketogenic diets can raise blood ketone levels, but ketone supplements such as ketone esters can also increase blood ketone levels. Exogenous ketone esters can reduce muscle tissue breakdown and stimulate anabolic activity in muscles by stimulating mTOR. (Nair et al., 1988; Vandoorne et al., 2017)

Both high protein and ketone esters show anabolic and anti-catabolic properties. In a remarkable study, scientists from France examined the effects of a high-protein diet and a ketone ester supplement on the maintenance of muscle mass and performance in young women on a diet.

HIGH PROTEIN VS KETONE ESTERS: WHICH IS BETTER FOR REDUCING MUSCLE LOSS

Young females were assigned to a 30% calorie-restricted diet but were assigned to three groups. All groups were instructed to maintain their normal physical activity and exercise program. The three groups were:

·      Calorie-restricted diet and high protein and a placebo (i.e., 2-2.2 g/kg/day .9-1 gram per pound of body weight)

·      Calorie-restricted diet plus exogenous ketone ester drink and low protein (20 grams of ketone esters 3 times per day).  Protein intake was set at .8-1.0 g/kg/day or .4-.5 grams of protein per day)

·      Placebo group: Low protein and a placebo Protein intake was set at .8-1.0 g/kg/day or .4-.5 grams of protein per day)

So why did the ketone ester group receive low protein? The researchers wanted to test if ketone esters are truly anti-catabolic.  The best way to have a person lose muscle is to place them on a low-protein diet while dieting. Previous research has shown that ketones are anti-catabolic when subjects are eating adequate calories. Therefore, this study wanted to test the responses to a calorie-restricted diet.

The researchers tracked body composition (i.e., signs of losing muscle mass), performed resting metabolic rate tests, took blood samples, and tested aerobic capacity (i.e., vo2máx).  A VO2max test is a maximal aerobic capacity test in which you run or bike until complete exercise exhaustion to test aerobic capacity.

RESTING METABOLIC RATE RMR TESTING

Resting metabolic rate is a measure of how many calories you are burning at rest. A DEXA is a body composition analyzer that measures bone mass, lean muscle mass, and % body fat.

Maintaining muscle mass is important for preserving metabolic rate. (Ravussin et al., 1986) If muscle mass is decreased with dieting, weight loss is harder because your body is burning fewer calories.

KETOSIS VS CALORIE RESTRICTION WITH HIGH PROTEIN

At the end of the 4-week study, only the high protein diet inhibited muscle tissue breakdown in the dieting females. The high protein diet also maintained aerobic capacity compared to the control group. Despite the preserved muscle mass, this did not prevent a decline in metabolic rate.  The exogenous ketone esters did not preserve muscle mass, but supplementation did have positive effects.