Lose fat, not muscle

If your goal is to look leaner, the scale is only half the story. The real win is losing fat while holding onto (or building) muscle — a.k.a. recomposition.

The two biggest levers?

• A reasonable calorie deficit (not a crash diet)
• High-ish protein + lifting (so your body has a reason to keep muscle around)

Why protein should be high during weight loss

When you’re in a calorie deficit, your body needs energy from somewhere. Ideally, it comes mostly from body fat — but without the right signals, some can come from lean tissue too.

Higher protein helps in a few ways:

• Muscle preservation: Protein supplies amino acids and supports muscle protein turnover. Combine that with resistance training and you’re basically telling your body: “Hey, we still need this muscle.”
• Better satiety: Protein is generally more filling per calorie, which makes the deficit easier to stick to.
• Slightly higher energy cost: Digesting and processing protein takes more energy than carbs or fat (small, but helpful).

In a controlled study where participants dieted hard and trained intensely, the higher-protein group gained more lean mass and lost more fat compared to the lower-protein group (Longland et al., 2016).

How much protein do I actually need in a deficit?

• Most active people cutting: 0.7–1.0 grams per pound of body weight per day
• In an aggressive deficit or with lots of training volume: consider the higher end of that range

If your body fat percentage is over ~30%, using total body weight will probably overestimate your protein needs. In this case, consider calculating your target using your height in centimeters (e.g., aim for about 1–1.2 grams per centimeter of height per day), or base it on your estimated lean body mass.

In physique-focused dieting situations for lean individuals, higher targets help reduce the risk of losing lean mass during a cut, and you may consider even up to 1.5g of protein per lb of bodyweight (for example, some contest prep guidelines use targets based on fat-free mass; see Helms et al., 2014).

Some individuals have a relatively low daily energy expenditure for their body weight, with typical total daily caloric burn falling around 10–15 calories per pound of body weight, depending on body composition and activity level. Individuals on the lower end of this range may find it more difficult to maintain a caloric deficit while hitting high protein targets (e.g., 0.7–1.0 g/lb body weight), because doing so can require an impractically high percentage of total calories from protein; in these cases, adding steady-state, low-fatigue cardio can be an effective way to increase average daily energy expenditure and make both calorie and protein goals more achievable. Importantly, baseline metabolic rate does not meaningfully decline with age between roughly 20 and 60 years when body size and composition are held constant, with a gradual age-related decline in energy expenditure typically beginning around age 60 (Science, 2021).

During caloric restriction, it's more important to focus on the percent of calories from protein, so you have enough room to get your protein in (aiming for your g/lb target) while meeting your calorie goal.

What about protein in a weight gain phase?

If you’re lifting and gaining weight, protein still matters — but more isn’t always more.

A large meta-analysis looking at resistance training and protein intake found benefits up to around ~0.7 g/lb/day, with diminishing returns beyond that point for muscle gain in most people (Morton et al., 2018). The optimal maximum isn’t known exactly — after about 0.7 g/lb, further increases don’t seem to provide much additional benefit for most, but some data suggest potential benefits could extend up to somewhere between 1 and 1.5 g/lb/day in select cases (such as during especially lean contest prep).

Practical take:

• Lean bulk (most lifters): ~0.7–1.0 g/lb/day
• There’s likely little to gain for most people by pushing much beyond about 1 g/lb/day — though it isn’t harmful, training quality, total calories, and sleep usually matter more than chasing ever-higher protein grams.

The crash diet trap: lose fast, regain faster (and end up “softer”)

Here’s the frustrating thing about crash diets:

1. You lose weight quickly (some fat, some muscle, some water)
2. You get burned out
3. You regain weight

If you end up at the same body weight you started with, you can still end up with a higher body fat percentage — because fat tends to come back easier/faster than muscle if the cut was harsh and training/protein weren’t protecting lean mass.

This “weight cycling can push body composition in the wrong direction” idea has been modeled and discussed in the scientific literature from a body composition autoregulation perspective (Hall, 2020).

The recomposition strategy

If you want “lose fat, not muscle,” here’s the playbook:

• Run a modest deficit you can sustain.
• Lift consistently (progressive overload beats perfection).
• Keep protein high (use the ranges above).
• Be patient: slow progress is usually the kind that sticks.

Want the app to do the math?

Fitness Tracker Chat can help you:

• Track protein grams and percent calories from protein
• Log food with just a photo or description
• Stay consistent
• Visualize your progress

You focus on the reps and real food. We’ll handle the counting.