If the Scale Is Dropping Fast, Lift Something
The scale gives you one number. It won’t tell you whether the four kilos you dropped last month came off your belly or off your legs, and that’s the difference you’ll feel two years from now.
It matters more this year than it did five years ago, because a lot of people are losing weight faster than bodies are used to. In the body composition analysis from the STEP 1 trial, adults who took semaglutide for 68 weeks lost around 19% of their fat mass and around 10% of their lean mass. The ratio still improved, so on balance the treatment worked. But a tenth of your lean tissue is a real amount to hand over, and lean tissue is what carries groceries up three flights when you’re 70.
I’m not here to tell you whether to take those drugs. That’s your doctor’s conversation, and for a lot of people the results have been good. My argument is narrower: whatever is pulling the weight off, fast loss without resistance training costs more muscle than it has to.
Two sessions a week changes the math
The clearest evidence I’ve seen is a 2018 meta-analysis by Sardeli and colleagues in Nutrients, which pooled six trials of older adults with obesity eating in a deficit. Groups that lifted three times a week for 12 to 24 weeks held on to 93.5% of the lean mass the diet-only groups lost. Same weight down, same fat down, muscle stayed put.
The S-LITE trial, published in the New England Journal of Medicine in 2021, ran the combination head to head. After everyone had lost weight on a low-calorie diet, participants spent a year on liraglutide, on exercise, on both, or on neither. The combination group cut body-fat percentage by 3.9 points, about double what either one managed alone (1.7 points for exercise, 1.9 for the drug). The drug moved the scale. The exercise decided what came off it.
The part that matters when you stop
Most people don’t stay on these drugs forever. In the STEP 1 trial extension, published in Diabetes, Obesity and Metabolism in 2022, participants regained about two thirds of the weight they had lost within a year of coming off treatment.
That’s the bit I’d plan around. Weight doesn’t come back as muscle by default; the body rebuilds fat far more readily than it rebuilds tissue you gave it no reason to keep. Give up 10% of your lean mass on the way down, regain most of the weight on the way up, and you can land on the same number you started at with a weaker body underneath it. What you do on the way down is what stops that.
What this looks like on a Tuesday
You don’t need a program with a name or a gym with a membership desk. You need to make a decent number of muscles work hard twice a week, then leave them alone.
- Two sessions a week, 30 minutes each, on days that aren’t back to back.
- Five movements per session: a squat, a hinge, a push, a pull, a carry.
- Two or three sets of each, stopping about two reps before your form falls apart.
- Add a rep or a little weight whenever the last set felt easy.
- Get protein into every meal. Clinicians treating people losing weight on GLP-1s are landing around 1.2 to 1.6 grams per kilo of body weight per day.
That last one is the hard part when your appetite has gone quiet. If a plate of food feels like a chore, eat the protein first and drop the carbs when you’re full.
Cardio isn’t the tool for this job. Walking is good for your heart, your head, and your blood sugar, and I’d still rather you walk than not. It just doesn’t tell your body that this muscle is in use and worth keeping. Only a genuinely hard contraction does that, which is why the fix is boring and specific: pick something heavy enough that the last two reps are ugly.
Open your calendar and put 30 minutes on two days this week, ideally the two you’re already home by six. First session: ten bodyweight squats, ten pushups against the kitchen counter, and one lap around the house holding the heaviest thing you own in each hand. Do it again on the other day.