Alan Aragon on Huberman Lab: How to Lose Fat and Gain Muscle

The old idea that you can only “use” 20–30 g of protein per meal for muscle is outdated. Newer studies show muscle protein synthesis (MPS) keeps increasing at least up to ~40–50 g, and in some designs even 100 g, especially after higher-volume training. Aragon and Schoenfeld’s review suggests aiming for about 0.4–0.6 g/kg (0.2–0.25 g/lb) per meal and ~0.7–1.0 g protein per lb of body weight per day for muscle and body composition. Once daily protein is in that optimal range, the exact timing around workouts is a “thin layer of icing on the cake,” not the cake itself.

Meta-analyses show that when total daily protein is ~1.6–1.7 g/kg (~0.7 g/lb) or higher, consuming protein immediately before vs. after training—or even 3 hours away from training—does not meaningfully change muscle or strength gains in most people. If you ate within a few hours before training, you already have amino acids circulating during and after the workout, so you do not need to sprint to a shake afterward. Practically, prioritize hitting daily protein across 2–4 meals; worry about “post-workout” only if you truly train after a long fast.

In fasted vs. fed cardio studies where total calories and protein are equal, fasted groups do oxidize more body fat during the workout itself—but the fed groups tend to burn more fat later in the day. Over 24 hours, fat loss is the same. A trial in college-aged women doing low–moderate intensity cardio on a calorie deficit found equal fat loss and lean mass retention whether they trained fed or fasted. Meta-analytic data support the same conclusion: choose fasted vs. fed based on preference and tolerance, not fat-loss magic.

Multiple studies now document “recomposition”: simultaneous lean mass gain and fat loss, often in people who aren’t in a strict deficit. Many of these use relatively modest caloric surpluses but very high protein—often 1.0–1.5 g per lb of body weight—combined with hard resistance training. Overfeeding protein alone (e.g., adding 80–100 g per day) in trained individuals often leads to either recomposition or no fat gain despite large calorie increases. Protein’s high satiety, high thermic effect, and support of training performance likely explain much of this effect.

Head-to-head diet studies show that when calories and protein are matched, high-carb vs. low-carb diets produce similar fat loss; macronutrient ratios matter far less than energy balance and protein adequacy. Added sugars should be kept modest (≈<10% of calories) mainly because they dilute nutrient density and promote hyper-palatability. Large intervention trials and meta-analyses generally do not support claims that aspartame, sucralose, or stevia at normal intakes cause weight gain or major metabolic harm; in fact, diet beverages often aid weight loss when they replace sugary drinks. Saccharin is the notable outlier with more concerning data, but it’s now rarely used.