The GLP-1 Starter Guide

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The scale is telling you half the story

If you're on semaglutide, tirzepatide, or a similar medication, the weight is probably coming off faster than anything you've tried before. That part is working.

The part nobody sits you down and explains is what you're losing. Weight loss is never purely fat. Some portion of every pound is lean tissue — muscle, organ mass, the structural material your body runs on. On a GLP-1, where total loss is large and appetite suppression is strong, that portion adds up to a real number.

One

Protein: the number that actually applies

The RDA for protein is 0.8 g per kilogram of body weight per day. That figure was set to prevent deficiency in a weight-stable adult. It was never designed for someone in a sustained calorie deficit, and it is close to useless as a target for you.

For preserving lean mass during active weight loss, the working range is 1.2 to 1.6 g per kilogram of ideal body weight — with evidence suggesting at least 1.6 g/kg/day is required to maximally preserve lean mass under energy restriction. Roughly double the RDA.

What that looks like in grams

Note the realistic ceiling: during titration, GI tolerance is often the binding constraint, and many people can't comfortably exceed 80–100 g/day until things settle. That's expected. Start at the bottom of your range and build.

Two

Distribution beats the daily total

Muscle protein synthesis doesn't run continuously. It's stimulated in pulses — each adequate serving switches it on for three to four hours, then it resets. So when you eat protein matters nearly as much as how much.

The most common pattern is also the worst: toast and coffee at breakfast, a small salad at lunch, most of the day's protein at dinner. That's one pulse a day.

Front-load it

Appetite typically declines as the day goes on and as the dose peaks. Protein you don't eat at breakfast is protein you're unlikely to make up at 8pm.

Watch the calorie floor

Protein targets don't rescue you from eating too little overall. Sustained intake below roughly 1,200 kcal/day for women or 1,500 kcal/day for men accelerates lean mass loss regardless of protein. If you've been under that for more than a few days running, raise it with your prescriber.

Three

Eating enough when you're not hungry

You spent years fighting appetite, and now you have the opposite problem — hitting a nutritional target with no hunger signal to help. Eating has to move from something you do when prompted to something you schedule.

• Eat on a clock, not on a signal. Waiting to feel hungry means waiting indefinitely.
• Protein first, every meal. When tolerable volume is small, order matters.
• Four or five small meals rather than three larger ones. Easier to tolerate, and more synthesis pulses.
• Liquid protein when solids are a problem. A shake goes down when a chicken breast won't. That's a tool, not a compromise.
• Don't drink your calories at mealtime. Fluid takes up limited stomach volume. Hydrate between meals.

Four

What the research says about muscle

The honest version, without the alarmism you'll find on social media and without the dismissiveness you'll sometimes get in a seven-minute appointment.

Two things are true about that number at once.

It is not dramatically different from dieting. Lose weight by any method and a similar proportion comes from lean tissue. The medication isn't doing something uniquely destructive.

But the absolute amount is larger, because the total loss is larger. A quarter of 40 pounds is far more lean tissue than a quarter of 12 pounds. The proportion is ordinary; the magnitude is not. That's why this matters more here than on your last diet.

The intervention that changes it

Resistance training is the lever with the best evidence behind it. Training two to three times weekly during GLP-1 therapy has been associated with a 30–50% reduction in fat-free mass loss versus no training. Nothing else in the toolkit has that effect size.

Five

The side effects nobody warns you about

Nausea

The most reliable dietary lever is fat density. High-fat, fried, or very rich meals predictably trigger nausea, more so as the dose climbs. Leaner preparations, smaller portions, slower eating. Nausea that stops you eating for days is a prescriber conversation, not a food-tweak conversation.

Constipation

Common, and largely a consequence of eating less and drinking less. Hydration first, then fibre — 25–35 g/day where tolerated, increased gradually. If that isn't enough, ask your prescriber rather than working through the pharmacy aisle alone.

Fatigue

Usually a symptom of something else on this list: under-eating, dehydration, or too little protein. Check those three first.

Losing weight but feeling weaker

Take it seriously. Strength falling faster than weight is the pattern most consistent with losing lean tissue rather than fat.

Six

What to ask at your next appointment

The short version

If you remember five things

1. Protein: 1.2–1.6 g per kg of ideal body weight, daily. Roughly double the RDA.
2. Spread it: 25–40 g per meal, three or four times a day. Front-load breakfast.
3. Lift two or three times a week. The best-evidenced single intervention — a 30–50% reduction in fat-free mass loss.
4. Eat on a schedule, not on hunger. And don't fall below your calorie floor.
5. Track strength, not just the scale. Weight down with strength held is a different outcome from weight down with strength down.

ASP-1 was formulated for exactly this problem — protein built for people whose appetite is suppressed and whose priority is holding onto muscle.