Many athletes cut weight to enhance performance, but how much protein should you consume to protect muscle mass and strength when dieting?
Overview
- What did they test? The impact of different protein intakes (1.2, 1.6, and 2.2 g/kg/day) during a moderate calorie deficit (~25%) on fat-free mass (FFM), resting energy expenditure (REE), and strength performance in recreational athletes.
- What did they find? All groups improved their performance, lost fat, and increased FFM, and there were minimal differences between protein groups.
- What does it mean for you? Protein intake of 1.2g/kg/day may be enough to prevent FFM losses with moderate caloric deficits in people who do not have a lot of resistance training experience.
What’s The Problem?
When people diet, one of their main goals is to maintain as much muscle as possible, which should help keep their strength and performance intact (and make them look more muscular). One common strategy to achieve this is to increase protein intake. Research consistently supports that consuming moderate to high amounts of protein helps prevent muscle loss during dieting, especially in overweight or less-active populations 1. However, whether these findings apply to people who exercise regularly, such as athletes, is less clear.
For those already engaged in resistance training, some evidence suggests elevated protein intake might offer additional muscle-sparing benefits during dieting. For example, male weightlifters were shown to maintain better muscle protein balance when consuming 1.6 g/kg/day protein compared to 0.8 g/kg/day 2. Similarly, trained males minimize muscle loss during short-term calorie restriction by consuming a high-protein diet (~2.3 g/kg/day) compared to a lower-protein diet (1.0 g/kg/day) 3. During a significant energy deficit, consuming 2.4 g/kg/day of protein was more effective than 1.2 g/kg/day in increasing lean body mass (LBM) and reducing fat mass, particularly when combined with high-volume resistance training 4. Furthermore, even during periods of calorie balance, resistance-trained females consuming higher protein have been shown to significantly increase muscle mass compared to those on lower protein intakes 5. Yet, there's still an important gap in understanding how different protein levels affect muscle and performance during calorie restriction.Currently, the International Society of Sports Nutrition recommends active individuals consume between 1.2-2.0 g/kg/day of protein 6, a range somewhat supported by a meta-analysis that found ~1.6 g/kg/day is optimal when coupled with resistance training 7. Last month, I wrote an article on a new meta-analysis that found protein intake of 1.9 g/kg of body mass per day or 2.5 g/kg of fat free mass (FFM) per day is associated with less FFM loss during energy restriction. Intakes above these values, specifically up to 3.2 g/kg of body mass or 4.2 g/kg of FFM were linearly associated with larger FFM gain. This suggests that higher protein is better for both maintaining muscle, and could even help people gain FFM in a caloric deficit. The current study under review adds to the stack of studies on the topic, so let’s dive in.
Purpose
To determine whether low (1.2g/kg/bw), moderate (1.6/kg/bw), or high (2.2 g/kg/bw) protein intake offer benefits for maintaining muscle mass and performance during weight loss.
Hypothesis
Higher protein intakes would better preserve muscle mass, strength, and resting metabolic rate.
