What I tell every patient who starts a weight-loss peptide
The weight comes off. So does something you wanted to keep. Here is the two-minute version of the conversation I have in the treatment room.
I see a lot of people on weight-loss peptides now. Semaglutide, tirzepatide, and the newer ones coming through behind them. Most of them are happy. The scales are moving for the first time in years and the food noise has gone quiet.
Then, around week eight, a different conversation starts. Flat in the afternoons. Hair shedding a bit. Gym numbers going backwards. Cramping at night. None of it dramatic. All of it the same cause.
You are eating a third less of everything.
That is the whole point of these drugs, and it works. Whether it is a GLP-1 on its own, a GLP-1 and GIP together, or one of the triple agonists, the mechanism is the same: you eat a lot less. In the trials, calorie intake dropped by up to 39%. [1] But the vitamins, minerals and protein you used to get came in with that food. Eat a third less food, you get roughly a third less of all of it.
Nobody plans for that. The prescription comes with advice about nausea and nothing about food.
The weight you lose is not all fat.
This is the part I wish more people were told up front. In the semaglutide trial, 40% of the weight lost was lean mass, muscle included. [2] Tirzepatide was similar on body scans. [3]
Muscle is what keeps your metabolism up and keeps the weight off once you stop the injections. Losing it is the expensive way to get lighter.
Losing muscle is the expensive way to get lighter.
The gaps show up in bloodwork first.
Long-term GLP-1 users see B12 drop by about 15% over a year, and one in five end up deficient. [4] Newly diagnosed vitamin D deficiency hits 13.6% within twelve months. [5] The newer peptides suppress appetite harder, not softer, so there is no reason to expect them to be kinder. Reduced thirst on all of them means electrolytes slide too.
That is the flat afternoons and the cramps. The drug is doing its job. The food has gone.
What I actually tell them to do.
Three things. Hit protein at every meal, even a small one. Lift something heavy twice a week. And cover the micronutrients and essential amino acids every single day, because you are not going to get them from two small meals.
The third one is where people fall over. Nobody wants to take nine bottles of pills on a stomach that already feels full.
So I point them at one scoop. Fireblood has all 9 essential amino acids, 15 vitamins in their active forms, 12 chelated minerals and the electrolytes, in a single 10g scoop that mixes into water or juice. Every dose is on the label. No sugar, nothing to keep you awake.
It tastes like vitamins, because that is what it is. Cold juice fixes that in ten seconds.
The peptide handles the appetite. The nutrition is still on you. One scoop a day and it is done.
See what's in the scoopSources
[1] Blundell J et al. Effects of once-weekly semaglutide on appetite, energy intake, control of eating, food preference and body weight in subjects with obesity. Diabetes Obes Metab 2017.
[2] Wilding JPH et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1), DXA substudy. N Engl J Med 2021.
[3] Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1), body composition substudy. N Engl J Med 2022.
[4] Observational cohort data on vitamin B12 status in long-term GLP-1 receptor agonist users, 2024.
[5] Retrospective cohort (n=461,382) of new vitamin D deficiency diagnoses after GLP-1 initiation, 2025.