For most of my patients the first genuine surprise is not the nausea. It is standing in front of an open fridge at seven in the evening, aware they have eaten almost nothing since breakfast, and feeling no particular interest in any of it.
The drug has removed the thing that used to make these decisions for you. Something has to replace it, and for the first time in most people’s lives that something has to be deliberate.
Protein first, and by a distance
Between a quarter and a third of the weight lost on these drugs is lean tissue if nothing is done about it. That is not unique to GLP-1s — it is true of most rapid weight loss — but the magnitude of the loss makes the arithmetic worse.
Two things move the number: resistance training, and protein. Protein is the one you control three times a day.
Target roughly 1.2 to 1.6 g per kg of body weight. If you have a lot of weight to lose, base it on a realistic goal weight rather than your starting weight, or the number becomes absurd. For most adults this lands between 90 and 130 grams daily.
The execution problem is real. Ninety grams of protein across three meals when each meal is the size of a side dish requires the protein to be the densest thing on the plate:
- Greek yoghurt, 15–20 g per pot
- Cottage cheese, around 25 g per cup
- Two eggs, 12 g
- A tin of tuna, 25 g
- Chicken thigh or breast, 25–30 g per palm-sized piece
- A ready-to-drink shake — Fairlife Core Power and Premier Protein are the two most people land on — 30 g in a container you can finish
Eat the protein portion first. On a day when you manage half a meal, the half you managed should be the part that mattered. This is covered in more depth in protein on a GLP-1, and the question of whether you need anything beyond food is worked through in do you need supplements on a GLP-1 and the GLP-1 supplement stack.
Fibre, and the constipation nobody plans for
Slowed transit plus reduced intake plus reduced fluid produces constipation with dreary reliability. It is one of the most common reasons people are miserable on a drug that is otherwise working.
Aim toward 25–30 g of fibre daily, and build up gradually — a sudden fibre load on a slow gut produces bloating rather than relief.
Practical sources that survive a small appetite: raspberries and blackberries, chia seeds stirred into yoghurt, black beans, lentils, oats, and a psyllium husk supplement such as Metamucil if food alone is not getting there. Psyllium needs a full glass of water to work and makes things worse without it.
Fat, in moderation rather than absent
Two competing pressures.
High-fat meals slow gastric emptying further and are the single most reliable trigger for nausea, reflux and that unpleasant sensation of food still being there hours later. Fried food at nine in the evening is asking for a bad night.
But very low fat is its own problem. Fat is what triggers the gallbladder to contract, and a stagnant gallbladder during rapid weight loss is how gallstones form. Fat also carries vitamins A, D, E and K.
Moderate is the answer: olive oil, nuts, avocado, oily fish, whole eggs — spread through the day rather than concentrated in one heavy meal.
1.2–1.6 g/kg
Daily protein target for preserving lean mass during rapid weight loss
25–30 g
Daily fibre target — build up gradually to avoid bloating
3–4
Small meals a day, rather than one large one
Fluid, and why plain water is not always enough
Coffee deserves its own note here, since for many people it becomes the largest thing they still consume by volume — see can you drink coffee on a GLP-1.
Appetite suppression takes thirst with it, and a meaningful amount of daily fluid normally arrives inside food. Reduce the food and the fluid goes too.
Dehydration on this drug class shows up as headache, fatigue, dizziness on standing and constipation — a symptom cluster people routinely attribute to the medication itself when it is simply water.
Sodium and potassium go out alongside the fluid, particularly if there has been vomiting or loose stools. Plain water alone can leave you flat. An electrolyte drink a few times a week is enough for most people; LMNT and Liquid I.V. are the usual choices, and a pinch of salt in water does the same job for pennies. The products are compared in the electrolyte roundup, and the cheapest routes across the whole category in value-ranked GLP-1 supplements.
The eating rules that actually help
- Small and often. Three to four modest meals rather than one large one. A large meal on a slow stomach is uncomfortable for hours.
- Slowly. Fullness now arrives late and abruptly. Eating fast means finding the wall long after you crossed it.
- Stop at the first signal. Not the third. The gap between comfortable and unwell is much narrower than it used to be.
- Not close to bed. Three hours before lying down, or you will meet your dinner again.
- Protein first, then vegetables, then the rest. Sequencing does the work when volume cannot.
You are no longer choosing what to eat. You are choosing what the small amount you can eat is going to be made of.
What to eat on a bad day
Dose-increase weeks have their own rules, and normal advice is useless during them.
Cool beats warm. Bland beats seasoned. Low odour beats aromatic — smell drives nausea more than taste does. Small and frequent beats a meal.
The reliable list: Greek yoghurt, cottage cheese, plain crackers, toast, ripe banana, clear broth, ice lollies, cold shakes, and sips of electrolyte drink rather than a full glass. Ginger genuinely has some evidence behind it for nausea; ginger chews such as Gin Gins are as good a delivery method as any.
One or two poor days do not undo anything. The goal on those days is fluid and a little protein, not a balanced diet.
The habit that outlives the prescription
The eating pattern you build now is the one you will have when the drug stops doing the enforcing.
That is the whole argument for doing this deliberately rather than simply eating less of what you used to eat. People who spend their year on a GLP-1 learning to build a plate around protein and vegetables come off it with a skill. People who spend it eating half a takeaway come off it with nothing but a smaller stomach and a returning appetite.