# How much whey protein per day is too much?

Source: https://www.healthnews24.co.za/answers/how-much-whey-protein-per-day-is-too-much/
Publisher: Healthnews24 (South Africa's supplement answer desk)
Updated: 2026-10-27

> For healthy adults in South Africa, whey becomes too much only when total daily protein climbs well above about 2.0–2.2 g per kg or causes stomach trouble. ISSN guidance is 1.4–2.0 g/kg a day and benefits plateau near 1.6 g/kg, so most people need one or two scoops (about 25–50 g). With kidney disease, follow medical advice.

Key facts:
- ISSN: 1.4–2.0 g of protein per kg a day for people who train; 2.3–3.1 g/kg may help preserve lean mass in trained people who are dieting.
- Morton et al. (2018): muscle benefits plateau near 1.6 g/kg a day (95% interval 1.03–2.20).
- Most people need only one or two whey scoops (about 25–50 g protein) a day.
- High-protein diets have not been shown to harm healthy kidneys; chronic kidney disease needs medical advice.

## How much whey protein per day is too much?

The question is really about total protein, not whey alone. The ISSN recommends 1.4–2.0 g of protein per kg of body weight a day for people who train. A meta-analysis of 49 trials found muscle benefits plateau near 1.6 g/kg a day (95% interval 1.03–2.20), with about 2.2 g/kg as a practical upper bound. Beyond that you pay for extra protein and risk digestive trouble without extra muscle. Short-term higher intakes up to 2.3–3.1 g/kg may help trained people keep lean mass while cutting.

## What does that mean in scoops?

| Body weight | Daily target at 1.4–2.0 g/kg | If food supplies 70% | Whey needed |
|---|---|---|---|
| 60 kg | 84–120 g | 59–84 g | about 25–36 g (one scoop) |
| 75 kg | 105–150 g | 74–105 g | about 31–45 g (one to two scoops) |
| 90 kg | 126–180 g | 88–126 g | about 38–54 g (up to two scoops) |

One scoop is typically 20–27 g of protein. A practical rule of ours: let powder supply no more than about a third of your protein and let food supply the rest. That is a guideline, not a regulatory limit.

## Is a large single dose a problem?

Not for muscle. Trommelen and colleagues (2023) found 100 g of protein after exercise produced a longer anabolic response than 25 g. But large servings tend to cause bloating and loose stools, especially with concentrate, milk or sugar alcohols ([why whey bloats](/answers/does-whey-protein-cause-bloating/)).

## What are the real risks?

- **Kidneys:** high-protein diets have not been shown to harm healthy kidneys, but people with chronic kidney disease should follow their doctor or dietitian ([whey and kidneys](/answers/is-whey-protein-safe-for-kidneys-south-africa/)).
- **Digestion:** gas, cramps or diarrhoea from lactose or sweeteners.
- **Allergy:** cow's-milk allergy rules out whey.
- **Contaminants:** more scoops mean more exposure. Consumer Reports' 2025 US testing found dairy-based powders generally had the lowest lead, though the picture varies by product.
- **Crowding out food:** shakes can replace fibre-rich meals.

Under-18s, pregnant women and anyone on medication should meet protein needs through food first and ask a professional before adding powder ([can teenagers take whey](/answers/can-teenagers-take-whey-protein-south-africa/)).

## What warning signs should you act on?

Persistent diarrhoea, swelling or rash, dark urine, flank pain, or any liver or kidney diagnosis: stop and see a doctor. Take stock of total daily protein, not scoops, using [how much protein per day](/answers/how-much-protein-per-day-south-africa/). For a tub, see the [best whey protein in South Africa](/best/best-whey-protein-south-africa/).

## Sources

- [ISSN Position Stand: Protein and Exercise (Jäger et al., JISSN 2017)](https://pubmed.ncbi.nlm.nih.gov/28642676/)
- [Morton et al. 2018, Protein supplementation and resistance-training-induced gains: systematic review, meta-analysis and meta-regression (BJSM)](https://bjsm.bmj.com/content/52/6/376)
- [Trommelen et al. 2023, The anabolic response to protein ingestion during recovery from exercise has no upper limit (Cell Reports Medicine)](https://pmc.ncbi.nlm.nih.gov/articles/PMC10772463/)
- [OPB/NPR (Oct 2025): Consumer Reports finds lead in popular protein powders](https://www.opb.org/article/2025/10/16/consumer-reports-finds-lead-in-popular-protein-powders/)