How much protein you actually need
Protein need scales with your body weight and what you’re asking your body to do, not with a single number that fits everyone. The government’s RDA of 0.8 grams per kilogram, about 0.36 grams per pound, is a floor for preventing deficiency in sedentary people, not a target for someone losing weight or building strength.
The ranges most sports-nutrition and obesity research supports look like this:
| Your goal | Protein target | For a 180 lb (82 kg) person |
|---|---|---|
| Maintain weight | 1.2–1.6 g/kg | ~98–131 g/day |
| Lose weight (in a deficit) | 1.6–2.0 g/kg | ~131–164 g/day |
| Build muscle | 1.6–2.2 g/kg | ~131–180 g/day |
Notice that losing weight calls for more protein than maintaining, not less. That’s the counterintuitive part most people get wrong: when you’re eating less overall, protein is the nutrient you most need to protect.
Why protein is non-negotiable in a deficit
When you lose weight, some of what you lose is fat and some is lean tissue (muscle, mostly). How much of each depends heavily on two things: how much protein you eat and whether you do any resistance training. Eat enough protein and lift, and the large majority of what you lose is fat. Skimp on protein, and you give up more muscle than you need to.
That matters beyond appearance. Muscle is metabolically active: it’s a big part of what determines how many calories you burn at rest. Lose a lot of muscle and you lower your metabolic rate, which makes maintaining your loss harder and regain easier. Protein is the single most important dietary lever for keeping that from happening.
Protein on a GLP-1
GLP-1 medications like Ozempic, Wegovy, Zepbound, and Mounjaro work largely by cutting appetite, which is exactly why they create a protein problem. When you’re only hungry for a fraction of what you used to eat, protein is usually the first thing that falls short, because it’s the most filling macronutrient and the easiest to skip when nothing sounds good.
The research on rapid weight loss is consistent: fast loss with inadequate protein means a larger share of the loss comes from muscle. Analyses of GLP-1 trials have flagged that a meaningful portion of the weight lost can be lean mass. The countermeasures are the same two levers as always, just more important here:
- Hit the higher end of your protein range (around 1.5–2.0 g/kg) even when you’re not hungry. Tick the GLP-1 box above and the calculator adjusts for this.
- Eat protein first at every meal and front-load it at breakfast, when appetite is often highest and nausea lowest.
- Add resistance training two to three times a week. Protein gives your body the material; lifting gives it the reason to keep the muscle.
This is the whole logic behind pairing a GLP-1 with a protein-forward diet and, for many people, a supplement stack built around protein and creatine.
Getting it in: practical targets
Spreading protein across the day helps your body use it. Aim for 25–40 grams per meal across three or four eating occasions rather than one giant serving. Rough anchors: a palm of chicken or fish is ~25–30 g, three eggs ~18 g, a cup of Greek yogurt ~20 g, a scoop of whey ~25 g. On low-appetite days, a protein shake is a legitimate way to hit the number when solid food is a struggle.
Limitations
This calculator uses total body weight, which is the simplest approach and matches most tools, but if you have a large amount of weight to lose, targeting protein based on your goal weight or lean body mass is often more precise (and lower). If that’s you, the lean body mass calculator gives a more tailored floor. And anyone with kidney disease should set protein targets with their doctor, not a calculator. These figures are general education, not a personalized medical or nutrition prescription.