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Whey or plant protein: how to choose

Whey or plant protein? India's dietary guidelines start with food. If you are choosing a powder anyway, compare the protein per 100 g, the ingredients and the allergens.

KiloCare Team · · How we write and review

2 tubs sit side by side on the shop shelf. One says whey, and the other says plant. Both say high protein on the front.

One label promises muscle. The other promises clean and natural. Neither tells you whether you need a powder at all, or which one suits your diet.

Do you need protein powder?

India's ICMR-National Institute of Nutrition writes in its 2024 Dietary Guidelines for Indians: "Protein powders are unnecessary for normal healthy life."[1]

The guideline advises getting good-quality protein from a varied diet: cereals with pulses, milk and curd, nuts and seeds. It advises against protein supplements to build muscle mass.[1] It names both kinds of powder, made from whey or from plants such as soya, peas and rice.[1]

So for a healthy adult who eats a varied diet, protein powder is not needed. Some people cannot eat enough protein from food, or have a medical or nutritional need. A qualified dietitian or doctor can help them decide.

If you are considering a powder, the next step is to understand what is in it: the protein per serving, the ingredients, the allergens and the evidence behind its claims.

What protein does, and where you get it

Of the 20 amino acids the body uses, 9 must come from food.[1] Our article on what protein does covers them and the foods that supply them.

NIN sets the allowance for healthy adults at 0.83 g of protein per kg of body weight a day, about 54 g for a 65 kg adult.[1]

A typical adult diet in India often already gives 60 to 70 g a day.[1] These figures are for healthy adults. If you are older, losing weight, eating less than usual, or have a health condition, ask a dietitian or your doctor how much protein you need. If you have kidney disease or have been told to limit protein, ask your doctor how much protein is right for you.

Pulses, soya, beans and peas, milk and curd, eggs, fish and meat all supply protein.[1] Eating cereals with pulses, about 3 parts cereal to 1 part pulse by raw weight, can meet the need for all the essential amino acids.[1] Rice with dal, or roti with chana, are familiar ways to do this. Anyone who takes medicine for diabetes should check with their doctor before changing how much rice or roti they eat.

What whey is

Whey is one of the 2 main groups of milk protein. Casein makes up about 80% of milk protein, and whey the other 20%.[7]

Whey powders include concentrate and isolate. To make them, the protein is separated from the milk's lactose and fat. Concentrate is filtered less and usually keeps more lactose and fat.[2]

Isolate is filtered further, so more of it is protein: over 90% by dry weight, against 29% to 80% for concentrate.[2] If lactose troubles you, check the label: isolate usually has less, but the amount varies by product.

Whey is a high-quality protein. About half of it by weight is essential amino acids, and about 11% of its protein is leucine, one of the highest of any source.[2] Leucine helps start muscle protein building, but the body needs all the essential amino acids to keep it going.[2]

What plant protein is

Plant protein powders use peas, soya, rice, pumpkin seeds, or a blend. A soy isolate and a pea and pumpkin seed blend can differ in their protein, their amino acids and their other ingredients.

Soy is a complete protein, and better studied than pea, rice and other plant proteins. One sports nutrition review rates it lower in quality than milk protein. It cites a short study in which soy raised muscle protein building less than whey in the hours after exercise.[2]

Cereals are low in lysine, an essential amino acid. Pulses are very slightly low in the sulphur amino acids.[3] Each fills the other's gap, which is why combining them works.[1] The UN's food agency treats protein quality the same way: across a mixed diet, a better protein can make up for a weaker one.[4]

A review of vegetarian diets in Western countries found that you do not need to combine them in the same meal. A reasonable variety over the day appears to be enough, as long as you eat enough protein in total.[3]

Is whey better for building muscle?

A 2021 trial followed 38 untrained young men through 12 weeks of supervised resistance training. The 19 who were already vegan took soy protein. The 19 who ate meat took whey. Both groups were topped up to about 1.6 g of protein per kg a day, about twice NIN's allowance for healthy adults. Both gained similar leg muscle and leg-press strength, with no significant difference between them.[5]

A 2025 review compared plant and animal protein in adults. In 30 trials that measured muscle mass, animal protein did slightly better.[6] The difference was mainly in adults under 60, and in trials with resistance training.[6]

The same review found no significant overall difference in strength or physical performance. In adults aged 60 and over, lower-body strength was better with animal protein.[6] In 17 trials comparing soy with milk protein, muscle mass did not differ.[6] Only 15 of its 43 trials were rated at low risk of bias.[6]

So protein source can matter a little. Total protein, the type of plant protein, and exercise matter too. In exercising adults, resistance exercise and protein work together.[2]

Digestion and allergies

A milk allergy and lactose intolerance are different conditions. In a milk allergy, the immune system reacts to milk protein. In lactose intolerance, the body cannot digest the sugar in milk, because it lacks an enzyme called lactase.[7]

Whey is a milk protein, even in an isolate with little lactose. Drink mixes and body-building drinks commonly contain whey, so people with a milk allergy need to read labels closely.[7]

A plant powder has no milk ingredients if every ingredient is from plants. It can still contain soy or another allergen. Some labels add a note such as "may contain traces of milk", but these notes are voluntary.[7] A label without one is not proof that there is no milk. If you have a milk allergy, ask your doctor or allergist before you choose.

Sweeteners, gums, fibre and serving size can also change how a shake suits you. If one shake upsets your stomach, check that product's ingredients before you rule out a whole type.

Whey and plant, side by side

  • Source. Whey: milk. Plant: soya, peas, rice, seeds or a blend.
  • Essential amino acids. Whey: rich in them, and in leucine. Plant: varies with the source and blend.
  • Milk ingredients. Whey: yes. Plant: none, if every ingredient is from plants.
  • Milk allergy. Whey: a milk protein, so ask your doctor first. Plant: read the ingredients and the allergen line.
  • Lactose. Whey: isolate usually has less than concentrate. Plant: none from plant ingredients.
  • Protein per 100 g. Both: read the label for that product.
  • Cost. Both: work out the cost of each serving.

5 questions to ask before you choose

Tick them off as you read a label, or copy them for later.

Before you choose a protein powder

A lab report on what a powder contains does not show that it improves your health.

Weight care and protein

No protein powder, whey or plant, is a weight-loss treatment. A powder adds calories as well as protein, so how it fits depends on the rest of what you eat. Protein from food comes first.

If you are managing your weight, ask your doctor or dietitian whether you need more protein, and whether food can provide it.

Which one, if any

Whey may suit you if you eat dairy and want a high-quality, well-studied source. A plant powder may suit you if you avoid dairy or eat vegan. If you already get enough protein from food, you may not need either.

Back at the shop shelf, you turn both tubs round and read the backs.

Speak to your doctor or dietitian before using a protein supplement if you:

  • have a milk or other food allergy
  • have kidney or liver disease, or diabetes
  • are pregnant or breastfeeding
  • take a medicine that reduces your appetite
  • have been told to limit protein
  • are buying it for a child

India's 2024 dietary guidelines say protein powders are unnecessary for normal healthy life, and that a varied diet, even a vegan one, easily meets protein needs if it combines cereals and pulses. This is for healthy adults. If you are older, losing weight or eating less than usual, ask a dietitian or your doctor how much protein you need.

Not for everyone. Whey is a high-quality milk protein. Plant powders vary by source and blend. In trials, the difference between animal and plant protein for muscle was small. Compare the actual products and your own diet.

Whey is a milk protein, so it can cause a reaction in people with a milk allergy. Lactose intolerance is a different condition. Ask your doctor before you choose any protein powder.

Sources

  1. ICMR-NIN Expert Committee. Dietary Guidelines for Indians - 2024. Hyderabad: ICMR-National Institute of Nutrition; 2024. Available from: nin.res.inCited atp. 61, Guideline 8pp. 57, 61p. 59p. 57p. 58p. 57pp. 59, 61p. 58p. 58
  2. Jäger R, Kerksick CM, Campbell BI, Cribb PJ, Wells SD, Skwiat TM, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. doi:10.1186/s12970-017-0177-8. PMID: 28642676. Available from: doi.orgCited atPreparation methods of various proteinsPreparation methods of various proteinsMilk proteins; Health benefits of milk-based proteinsProtein qualityMeat vs. plant based proteinsPosition statement, point 1
  3. Mariotti F, Gardner CD. Dietary Protein and Amino Acids in Vegetarian Diets-A Review. Nutrients. 2019;11(11):2661. doi:10.3390/nu11112661. PMID: 31690027. Available from: doi.orgCited atSection 3Section 4
  4. Food and Agriculture Organization of the United Nations. Dietary protein quality evaluation in human nutrition: report of an FAO Expert Consultation. Rome: FAO; 2013. FAO Food and Nutrition Paper 92. Available from: fao.orgCited atp. 22, §4.1
  5. Hevia-Larraín V, Gualano B, Longobardi I, Gil S, Fernandes AL, Costa LAR, et al. High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores. Sports Med. 2021;51(6):1317-1330. doi:10.1007/s40279-021-01434-9. PMID: 33599941. Available from: pubmed.ncbi.nlm.nih.govCited atAbstract
  6. Reid-McCann RJ, Brennan SF, Ward NA, Logan D, McKinley MC, McEvoy CT. Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Nutr Rev. 2025;83(7):e1581-e1603. doi:10.1093/nutrit/nuae200. PMID: 39813010. Available from: pmc.ncbi.nlm.nih.govCited atResultsResults; Table 3ResultsResults, subgroup analysisResults; Discussion
  7. American College of Allergy, Asthma & Immunology. Milk & Dairy [Internet]. ACAAI; [cited 2026 Oct 13]. Reviewed for accuracy 21 Mar 2019. Available from: acaai.orgCited atManagement and TreatmentMilk Allergy or Lactose Intolerance?Management and TreatmentManagement and Treatment