Guides

What the research says about keeping muscle.

Plain-English answers to the questions people ask when they're losing weight. Every number links to the study or guideline it came from.

GLP-1

Does Ozempic Cause Muscle Loss? What the Body Scan Studies Show

Semaglutide (Ozempic®, Wegovy®) and tirzepatide (Mounjaro®, Zepbound®) cause large weight loss, and some of that loss is lean mass. In body scan studies, lean mass made up about 38–40% of the weight lost on semaglutide and about 25% on tirzepatide. Lean mass includes muscle plus water, organs and connective tissue. Enough protein and regular strength training help you keep more muscle.

6 min read · 8 sources

GLP-1

How Much Protein Should You Eat on a GLP-1 Medication?

A 2025 joint advisory on nutrition for GLP-1 therapy notes that protein targets of 1.2–1.6 g per kg of body weight a day have been proposed during active weight loss, with 80–120 g a day as a simpler alternative. If your BMI is 30 or above, basing the math on an adjusted body weight is more realistic. Spread protein across small meals when appetite is low.

6 min read · 6 sources

GLP-1

What Happens When You Stop Ozempic or Mounjaro?

In the two largest trials that followed people after stopping, most regained a meaningful share of the weight they had lost. People who stopped semaglutide regained about two-thirds of their loss within a year, and people switched from tirzepatide to placebo regained weight while those who continued kept losing. The trials did not report what the regained weight was made of.

6 min read · 6 sources

Fat loss

How to Lose Fat Without Losing Muscle: The 3 Things That Matter

To lose fat while keeping as much muscle as possible, focus on three things: eat enough protein, do strength training at least twice a week (ideally three times), and lose weight at a steady pace of about 0.5–1 kg (1–2 lb) a week. Some lean mass loss is normal with any weight loss, but these habits help you keep more.

6 min read · 11 sources

Tracking

Signs You're Losing Muscle, Not Fat (and How to Check at Home)

The clearest at-home sign that you're losing muscle rather than fat is strength going backwards for several weeks while your weight falls. Other clues include very fast weight loss, a scale that drops while your waist barely changes, and everyday tasks feeling harder. The scale alone can't tell you, so check weight trend, strength and waist or smart-scale trend together each week.

6 min read · 7 sources

Tracking

Are Smart Scales Accurate for Body Fat? What the Studies Say

Smart scales are usually accurate for body weight but not for body fat. Studies comparing consumer scales with DXA scans found they underestimated fat mass and could be off by several kilograms for an individual. Treat the body-fat number as an estimate: use one scale in the same conditions, compare weekly averages, and pair that trend with your weight and strength progress.

6 min read · 8 sources

Strength

Muscle Loss After 40: What Happens and What Helps

Yes, gradually. Muscle mass and strength both decline with age, and strength tends to fall faster than muscle size, so everyday tasks can feel harder before you notice any visible change. This is normal aging, not a diagnosis. Regular strength training on at least two days a week and enough protein are what guidelines consistently point to, especially when you are losing weight.

6 min read · 12 sources

Getting started

Getting Back in Shape After a Baby, an Injury or Years Off

Start by getting cleared where it applies: at your postnatal check after a baby, or by your clinician or physical therapist after an injury. Then begin smaller than you think, with walking and a simple full-body strength routine on two days a week, and build up slowly. Stop if something hurts, and measure progress by getting stronger, not only by the scale.

7 min read · 9 sources

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