An Introduction to Protein Shakes: Who Needs Them and What to Check
Protein shakes used to be something only bodybuilders bought in giant tubs. Now they sit on supermarket shelves next to the breakfast cereal, promoted for weight loss, healthy ageing and busy mornings. They can be genuinely useful, but most people do not need them, and it helps to understand what they are, how much protein you actually need, and what to look for on the label before you spend money on them.
What is a protein shake?
A protein shake is simply a drink made by mixing protein powder with water, milk or a milk alternative, or bought ready to drink. The powders are concentrated protein extracted from foods. The most common types are:
- Whey, from milk. It is absorbed quickly and is rich in leucine, an amino acid involved in building muscle.
- Casein, also from milk, which is digested more slowly.
- Soy, a complete plant protein.
- Pea, rice, hemp and blends, often combined to improve the balance of amino acids for people who avoid dairy.
- Egg white protein, for people who avoid dairy but eat eggs.
Shakes are a convenient way to get protein. They are not a different or better kind of protein than you get from food.
How much protein do you need?
Protein needs depend on body size, age and how active you are. A common reference point for healthy adults is the long-standing recommended dietary allowance of about 0.8 grams of protein per kilogram of body weight per day. For a 70 kg adult, that is roughly 56 g a day, an amount most people in wealthy countries already exceed through ordinary meals. MedlinePlus, from the US National Library of Medicine, notes that one ounce (about 30 g) of most protein-rich foods, such as meat, fish or a large egg, provides around 7 grams of protein.
People who exercise hard may benefit from more. The International Society of Sports Nutrition’s position stand on protein and exercise suggests that an overall daily intake of 1.4 to 2.0 g per kilogram is sufficient for most exercising individuals, and that it can come from food, supplements or both. A widely cited 2018 meta-analysis in the British Journal of Sports Medicine, pooling 49 studies, found that protein supplements modestly increased gains in muscle mass and strength during resistance training, but that intakes above about 1.6 g per kilogram per day gave no further gains in muscle.
In other words: more protein helps only up to a point, and only alongside training.
Who might find protein shakes useful?
- People doing regular strength training who struggle to hit their protein target from meals.
- Older adults with small appetites. Muscle mass declines with age, and getting enough protein alongside strength exercise helps maintain it. A shake can help when large meals are unappealing, but a doctor or dietitian should guide this for anyone who is losing weight unintentionally.
- People with higher needs during recovery, for example after illness or surgery, under medical advice.
- Vegans and vegetarians who find it hard to eat enough protein, although beans, lentils, tofu, tempeh and soya milk usually cover needs well.
- Anyone who needs a quick option occasionally, such as a post-workout snack or a breakfast on the go.
Protein shakes and weight loss
Protein tends to be filling, and higher-protein diets can make it easier to control appetite when cutting calories. But a shake still contains calories, and many ready-made ones contain added sugar. Adding a shake on top of your usual diet can make you gain weight rather than lose it. If you use a shake as a meal replacement, check that it provides a balanced mix of nutrients, not just protein, and that it fits into an overall plan you can sustain.
Possible downsides
They are supplements, not medicines
In the US, dietary supplements are regulated differently from medicines. The Food and Drug Administration explains that it does not have the authority to approve dietary supplements before they are marketed. Quality varies between brands. Independent testing marks from third-party certification programmes can offer some reassurance that a product contains what the label says and is free of banned substances, which matters for competitive athletes.
Added ingredients
Many products include sweeteners, thickeners, added sugars, caffeine or herbal extracts. Some sold for “fat burning” or “lean muscle” contain stimulants. Read the ingredients list, not just the front of the pack.
Digestive effects
Whey and casein contain some lactose, which can cause bloating in people who are lactose intolerant. Whey isolate contains less lactose than whey concentrate. Some sweeteners, such as sugar alcohols, can also upset the gut.
Kidney disease
For healthy people, normal protein intakes are not known to harm the kidneys. People with chronic kidney disease are different: the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) notes that some people with CKD may need moderate amounts of protein so waste does not build up in the blood, and advises working with a dietitian to find the right balance. If you have kidney disease, do not start protein supplements without advice.
How to choose a protein powder
| Check | What to look for |
|---|---|
| Protein per serving | Typically 20 to 30 g; more is not necessarily better |
| Ingredients list | Short and recognisable; limited added sugar |
| Third-party testing | An independent certification mark, especially if you compete in sport |
| Dietary needs | Lactose-free, vegan or allergen-free if you need them |
| Price per gram of protein | Often a better comparison than price per tub |
Food first
For most people, food is the simplest source of protein, and it comes with fibre, vitamins and minerals that powders lack. Eggs, Greek yoghurt, milk, cheese, fish, chicken, beans, lentils, tofu, nuts and seeds all contribute. A glass of milk or a pot of yoghurt after exercise does much the same job as a shake, often for less money.
When to see a doctor
Talk to a doctor or registered dietitian before using protein supplements if you have kidney or liver disease, are pregnant or breastfeeding, are trying to gain weight after an illness, or are losing weight without trying. If you notice persistent digestive symptoms after starting a shake, stop and seek advice.
This article is general information, not medical advice. A doctor or dietitian can help you work out how much protein is right for you.
