Study under review: Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial
Losing fat while gaining muscle is generally considered the holy grail of dieting. Unfortunately, the vast majority of weight loss studies show that as much as 20-30% of the body weight lost during dieting is from lean body mass (including muscle mass). Maintenance of muscle mass is important for everyone, but becomes particularly relevant when athletes are trying to lose weight while improving performance, as well as for older adults due to the importance of muscle mass for overall health and mobility.
Resistance training is one of the most important factors for maintaining muscle mass while dieting, with other major ones shown in Figure 1. It can attenuate the loss of muscle by stimulating muscle protein synthesis (MPS). And it’s also been well established that protein supplementation can augment the effects of strength training on MPS. However, the optimal protein intake to promote weight loss while retaining and/or increasing muscle mass has yet to be firmly determined.
Reference: Atherton et al. J Physiol. 2012 Mar.Being in an energy deficit appears to reduce basal MPS, as well as the sensitivity of MPS from feeding. However, a resistance training program along with increased protein intake can synergistically increase rates of MPS. This is particularly valuable during an energy deficit, as one study showed consuming 30 grams of protein after resistance exercise led to a greater stimulation of MPS than the consumption of 15 grams of protein. Another study found that 1.6 grams of protein per kilogram of bodyweight (2x the Recommended Dietary Allowance, or RDA) was able to reduce the loss of lean body mass during energy restriction, while yet another study suggested that more than two grams per kilogram of bodyweight may be needed to maintain lean mass when dieting.
Beyond resistance training, high-intensity interval training during a calorie deficit can also help to retain lean mass. A further consideration is the effects of an energy deficit on hormone levels, with or without exercise. Hormones such as IGF-1 and testosterone may play a role in the maintenance of lean mass during an energy deficit combined with physical activity, though this remains somewhat of an open question.
With questions still remaining about the optimal protein intake and exercise regimens during an energy deficit, researchers designed a four-week study with participants undergoing an approximate 40% caloric reduction along with daily resistance or interval training, while consuming either moderate or higher protein intakes of 1.5x and 3x the RDA for protein. Changes in body composition, hormone levels, and indices of strength and aerobic capacity were measured. Unfortunately, measures of metabolic rate were not made either before or after the intervention.
Retention of lean body mass is important when dieting. Increased protein intake and resistance training can help preserve lean mass during a calorie deficit. This study was set up to test two different protein intakes consumed by people in a caloric deficit and following a daily exercise program.
Other Articles in Issue #16 (February 2016)
Promoting ‘high quality’ weight loss: protein and weights
By Stuart Phillips, PhD
Vitamin E bioavailability isn’t always the same
The vast majority of people don’t meet the recommended intake level for vitamin E. And it turns out that certain people may not absorb vitamin E as well as others, and they might actually be the ones who need it most.
Spice up your satiety?
The active ingredient in spicy food, capsaicin, seems to have some effect on satiety. But researchers weren’t quite sure what it was or how it happens, until this highly controlled experiment was done
Little bugs for big depression
Your gut and your brain communicate much more often than you’d think. In fact, all the time. Hence the potential for consuming gut inhabitants (aka probiotics) and impacting brain-related maladies
Fish oil incorporation: where do other fats fit in?
When you buy and take a fish oil supplement, the story doesn’t end there. It still needs to be incorporated into cell membranes. This study looked at how other fats may impact that process
The Tyranny of the Outlier: Focusing on the best of the best sometimes diminishes the rest of us
By Lou Schuler
Have a nice trip, see you next fall
Some preliminary evidence has pointed to a potentially greater risk of falls for elderly people taking vitamin D. That’s put to the test in this year-long randomized trial.
A vitamin D-efense against multiple sclerosis
MS involves a complex interplay between the nervous and immune systems (and potentially others as well). This is the first trial looking at the safety and immune impact of vitamin D supplementation for MS patients.
The newest index on the block… the hydration index!
Hydration has become more of a marketing term than a scientifically accurate one. These researchers created an index to specifically measure the hydration impact of different beverages, from milk to coffee to beer