Accepted answer
They are close to incompatible, and the thing to fix is the 900, not the protein. Here is the arithmetic that shows why, and then the food selection that gets you as far as food selection can get you.
Step 1: which body mass goes in the denominator
All three conventions exist in the literature and they are not interchangeable. Compute all three and take the middle:
Current body weight, 1.6 g/kg:
1.6 x 92.4 = 147.8 g -> call it 148 g
Goal body weight (say 72 kg), 1.6 g/kg:
1.6 x 72 = 115.2 g -> call it 115 g
Lean soft tissue from your DEXA, 2.2 g/kg LBM:
2.2 x 51.6 = 113.5 g -> call it 114 g
The convergence of the last two is not a coincidence: goal-weight scaling and lean-mass scaling are approximately the same calculation once you accept that fat mass has essentially no protein requirement. Current-body-weight scaling over-estimates the requirement for anyone carrying substantial fat mass, which is most people on these drugs. That single correction takes your target from 148 g to about 115 g and the problem becomes tractable.
Working target: 115-125 g/day. Treat 115 as the floor and anything above it as a bonus.
Step 2: the energy cost of protein, and why food choice is the whole game
115 g x 4 kcal/g = 460 kcal of the 900 kcal budget = 51%
But that is the cost of pure protein. Food comes with the fat and carbohydrate attached. The number that actually determines feasibility is protein density: grams of protein per 100 kcal of the food as eaten.
| Food (cooked, per 100 g unless stated) | Protein | Energy | g protein per 100 kcal |
|---|
| Whey protein isolate, dry powder | 90 g | 370 kcal | 24.3 |
| Prawns, boiled | 24 g | 99 kcal | 24.2 |
| Cod or haddock, baked | 23 g | 105 kcal | 21.9 |
| Tuna, tinned in water, drained | 24 g | 108 kcal | 22.2 |
| Egg white, raw | 11 g | 52 kcal | 21.2 |
| Chicken breast, skinless, roasted | 31 g | 165 kcal | 18.8 |
| Turkey breast, skinless | 29 g | 157 kcal | 18.5 |
| Greek yoghurt, 0% fat | 10 g | 59 kcal | 16.9 |
| Cottage cheese, low fat | 11 g | 72 kcal | 15.3 |
| Sirloin steak, lean, grilled | 29 g | 206 kcal | 14.1 |
| Tofu, firm | 17 g | 144 kcal | 11.8 |
| Whole egg, boiled | 13 g | 143 kcal | 9.1 |
| Lentils, boiled | 9 g | 116 kcal | 7.8 |
| Salmon, farmed, baked | 25 g | 232 kcal | 10.8 |
Now the feasibility test. What average protein density do you need to hit 115 g inside a given fraction of 900 kcal?
If protein foods may occupy 550 kcal of the 900:
required density = 115 g / 550 kcal x 100 = 20.9 g per 100 kcal
If protein foods may occupy 650 kcal:
required density = 115 / 650 x 100 = 17.7 g per 100 kcal
If protein foods may occupy 460 kcal (the theoretical floor):
required density = 115 / 460 x 100 = 25.0 g per 100 kcal
Look at the table. A required density of 25 exceeds every real food including isolate powder, so the theoretical floor is unreachable. A required density of 20.9 is reachable but only if essentially everything you eat is white fish, prawns, egg white, tinned tuna and isolate. A required density of 17.7 is comfortably reachable with chicken, turkey, 0% Greek yoghurt and one isolate serving, and leaves 250 kcal for vegetables and a little fat.
So: 115 g inside 900 kcal is possible, and it costs you roughly 650 of your 900 kcal, i.e. 72% of intake. That is a diet with essentially no discretionary energy in it at all.
Step 3: which do you fix
Fix the 900. Not by forcing food, which does not work when the appetite signal is genuinely absent, but by raising the energy density of what you already eat so the same volume carries more energy. Olive oil on the vegetables. Full-fat Greek yoghurt instead of 0%. Whole eggs alongside whites. Nuts as a deliberate item rather than an indulgence. Going from 900 to 1250 kcal changes the required protein density from 17.7 to about 11, which is the density of ordinary food, and the problem dissolves.
The reason to fix it in that direction rather than accepting 900 is that total energy availability, not protein alone, drives lean-mass retention. You can eat 115 g of protein at 900 kcal and still lose lean tissue, because a large fraction of that protein gets oxidised for energy rather than used for repair when the energy deficit is severe enough. Protein is not a substitute for calories. At 92.4 kg, 900 kcal is roughly a 60% deficit, and that is the variable doing the damage.
One thing worth raising with whoever prescribes for you: intake this low, sustained, is a reason to discuss whether your current dose is above what you need, rather than something to solve entirely with food engineering.
edited 5 Apr 2025 by lyoph_cake — added the method parameters
3The protein density table is the part I have wanted for two years. Prawns and egg whites being tied with isolate powder is not intuitive. – coldpack_88 11 days ago 4Agreed on fixing the energy first. Protein at a 60% deficit gets burned, not built with. – mateo_iglesias 2 months ago Worth adding that raising energy density also raises palatability, which is the actual mechanism by which people manage to eat more. – ilaria_bertone 4 months ago add a comment