How do you work out a client's protein needs?
In short: Multiply the client's body weight in kilograms by a factor that matches their age, activity and goal: 0.8 g/kg covers a healthy sedentary adult, 1.0 to 1.2 g/kg suits adults over 65, and 1.4 to 2.0 g/kg suits people who train. For clients with higher levels of body fat, applying the target to total body weight can give an unnecessarily high figure. Lean or fat-free mass, or a reference weight, may provide a more appropriate basis, using the method specified by the guideline or protocol you follow.
1 min 15 s videoCaptions onUpdated 4 October 2026
The starting ranges
Protein targets work best in grams per kilogram of body weight a day, because need follows body size and muscle mass. These are the ranges most practitioners work from.
| Client | Protein a day | Where it comes from |
|---|---|---|
| Healthy adult, little exercise | 0.8 g/kg | RDA, US Institute of Medicine |
| Adult over 65 | 1.0 to 1.2 g/kg | PROT-AGE Study Group |
| Over 65 with acute or chronic illness | 1.2 to 1.5 g/kg | PROT-AGE Study Group |
| Regular exercise or sport | 1.4 to 2.0 g/kg | ISSN position stand |
| Resistance training for muscle gain | About 1.6 g/kg, up to 2.2 g/kg | Morton et al. meta-analysis |
| Lean, trained, in an energy deficit | 2.3 to 3.1 g/kg of lean mass | Helms et al. review |
The 0.8 g/kg RDA is designed to meet the protein requirements of nearly all healthy adults. It isn't necessarily an optimal target for someone trying to preserve muscle while losing weight, and older adults generally need more protein because their muscles have a reduced anabolic response to protein.
Which body weight to use
Total body weight is a practical starting point for many clients. At higher levels of body fat, however, applying a high protein target directly to actual body weight can produce unnecessarily high protein prescriptions, because protein requirements do not increase in direct proportion to adipose tissue. For example, applying 1.6 g/kg to a 120 kg client gives 192 g of protein per day.
In these cases, alternative approaches can be considered:
- Lean or fat-free mass. If you have a reliable measure of body composition, protein can be calculated relative to lean or fat-free mass. The appropriate g/kg target depends on the client's circumstances and goal, so use a range supported for the population you're working with rather than applying one universal lean-mass target.
- Goal or reference weight. A realistic goal or reference weight can sometimes provide a more practical basis for setting protein than actual body weight. Use the reference-weight method specified by the guideline or protocol you're following rather than assuming a particular BMI cut-off.
- Adjusted body weight. Adjusted body weight is used in some clinical guidelines for people with obesity. The exact calculation varies between protocols, so use the method specified by the relevant guideline rather than assuming one universal formula.
A worked example
Two clients, both aiming to lose fat and doing resistance training twice a week.
For illustration, the lean-mass calculations below use 2.4 g/kg. This falls within the range reported for lean, resistance-trained athletes during energy restriction in the Helms review, but isn't a universal lean-mass target. The appropriate target depends on the population and goal.
| Method | Calculation |
|---|---|
| Client A: 72 kg, 32% body fat | |
| By body weight | 72 × 1.6 = 115 g |
| By lean mass | 72 × 0.68 = 49 kg lean mass; 49 × 2.4 = 118 g |
| Client B: 120 kg, 45% body fat | |
| By body weight | 120 × 1.6 = 192 g |
| By lean mass | 120 × 0.55 = 66 kg lean mass; 66 × 2.4 = 158 g |
| By realistic goal/reference weight (example) | 90 × 1.6 = 144 g |
For Client A, the two methods give almost the same answer. For Client B, they do not. Using total body weight produces a substantially higher target, while lean mass or a realistic goal/reference weight gives a more practical starting point. This is why, at higher levels of body fat, it can be useful to consider an alternative to actual body weight rather than automatically applying the same g/kg calculation. The appropriate method and target should be chosen for the individual client.
Spreading it across the day
A daily target of 150 g may be easier to reach when protein is distributed across meals rather than concentrated in one large evening meal. Total daily protein intake is the priority, but including a meaningful serving of protein at each meal can also help support muscle protein synthesis. Many clients eat relatively little protein at breakfast, so this can be an easy place to start. Eggs, Greek yoghurt or cottage cheese can substantially increase breakfast protein without requiring a much larger meal.
Plant-based clients can meet their protein requirements too. Some plant proteins have lower digestibility and/or lower amounts of particular essential amino acids than animal proteins, so food choice, total intake and variety become important. Include a range of protein-rich foods such as soy foods, legumes, grains, nuts and seeds across the day; some clients may benefit from targeting the higher end of an appropriate protein range.
Check for conditions or life stages that change protein requirements before applying a standard target. Chronic kidney disease may require an individualised protein prescription based on disease stage and treatment, so work within your scope and follow appropriate renal guidance or refer where necessary. Protein requirements also increase during pregnancy, so use pregnancy-specific recommendations rather than the standard adult ranges above. For clients using weight-loss medication, see protein needs on GLP-1 medication.
How to do it in Foodzilla
Foodzilla holds each client's protein target in grams on Health & Diet Goals. It can set protein from lean body mass for you, or you can type the number you've worked out.
- 1Go to Clients, open your client's dashboard and choose Health & Diet Goals, then the Nutrition tab. Daily Protein In shows the current target in grams.
- 2To set your own number, edit Daily Protein In. Daily Energy In changes by 4 kcal for every gram you add or remove, so check the energy target afterwards.
- 3To change protein and keep the energy target, open BMR Formula & Macro Ratios, move the Protein slider, check the grams in the preview and press Apply Changes.
- 4To have Foodzilla work from lean mass, add the client under Clients, then Add Client. Enter Body Fat under Body Measurements and choose Automatic (recommended), Katch-McArdle or Cunningham as the BMR Formula under Nutrition Goals. Their calculated protein is then 1.8 g per kg of lean mass to maintain, 2.2 g to gain and 2.4 g to lose, plus 0.2 g when their Body Fat Goal is below their current body fat, up to 2.6 g, and never more than 40% of energy.
- 5Open Understanding Your Client's Nutrition Calculations to see the lean mass sum Foodzilla used.
Good to know
- Check intake before you raise the targetLook at what the client eats now before you set a number. Going from 60 g to 140 g overnight rarely sticks. Adding 20 to 30 g a fortnight usually does.
- An existing split stays putIn Foodzilla, changing the BMR formula or goal weight on a client who already has targets keeps their macro split and rescales it. If you want protein from lean mass on an existing client, set the grams yourself.