The question of whether you can build muscle while in a calorie deficit has puzzled many fitness enthusiasts. Conventional wisdom suggests that a calorie surplus is necessary for muscle gain, while a deficit is crucial for fat loss. But what about trying to achieve both simultaneously?
Recent research led by Murphy and Koehler (2022) aimed to shed light on this topic by reviewing the effects of a calorie deficit on muscle gain. The findings indicate that while muscle mass gains are impaired by a calorie deficit, strength gains may not be as negatively impacted. Let’s dive deeper into what this means for your training and dieting goals.
The notion of losing fat while gaining muscle, known as “recomposition”, is appealing but often misunderstood. The idea of a quick transformation is frequently exaggerated by the fitness industry. While recomp can be achieved, it’s context-specific and generally more feasible for beginners or those with higher body fat percentages.
For those already well-trained or lean, recomp is likely a slow and challenging process. It often requires being at maintenance calories, consuming high protein, and engaging in resistance training, rather than being in a deficit.
Murphy and Koehler explored how an energy deficit impacts muscle mass and strength by analyzing data from multiple studies. Two primary analyses were conducted:
- Analysis A: Compared groups in an energy deficit versus groups not in a deficit, all engaged in resistance training.
- Analysis B: Included studies with only one condition (either a deficit group or non-deficit group) engaged in resistance training.
Both analyses primarily involved inactive or sedentary participants, mostly middle-aged women.
In both analyses, a calorie deficit impaired muscle mass gains or led to muscle mass loss. The magnitude of the deficit, participant weight, and age were significant factors, but sex was not. A deficit of around 500 calories per day, a common recommendation, impaired muscle gains but generally did not cause significant muscle loss. The results showed a linear relationship between deficit size and muscle mass loss, in that deficits smaller than 500 calories still generally allowed subjects to gain some fat-free mass (i.e. recomp), while deficits larger than 500 calories generally led to losses of fat-free mass (and the losses scaled with the magnitude of the deficit). Despite reductions in muscle mass, strength gains were not negatively impacted in the deficit groups. Participants continued to increase their strength during a calorie deficit.
While being in a calorie surplus is still optimal for gaining muscle, a moderate deficit (about 500 calories below maintenance) combined with resistance training and high protein intake can help preserve muscle during fat loss. The primary takeaway is that although gaining significant muscle mass in a deficit is unlikely, unless you’re a beginner, strength improvements can still be achieved. Additionally, maintenance phases with sufficient protein and resistance training can lead to muscle and strength gains.
If your goal is fat loss, consider:
- A moderate calorie deficit (~500 calories below maintenance).
- Regular resistance training (2+ times per week).
- Adequate protein intake (1.6-2.2g/kg of body weight).
Recomposition is possible, particularly for beginners or those with higher body fat, but significant muscle gains are more likely in a calorie surplus. Ultimately, your goals and training experience will guide whether a deficit or surplus is most appropriate for you.
