Do I need protein powder to build muscle?

No. Muscle protein synthesis responds to total daily protein and resistance training, not to the form the protein arrives in. A 2018 meta-analysis by Morton and colleagues found gains up to about 1.6 g per kilogram per day, with the confidence interval extending to 2.2. If food reaches that range, powder adds nothing.

Is whey better than casein?

Whey empties from the stomach faster and produces a sharper rise in plasma amino acids; casein produces a slower, flatter one. When total daily protein is matched, trials such as Soop 2011 found no difference in muscle protein synthesis. The choice is about digestion comfort and timing, not outcome.

What is the best protein powder type?

There is no best type in the sense of a superior outcome. Whey, casein and pea-rice blends produce equivalent results when grams are matched, as Lynch 2019 found over 12 weeks. The differences are price per gram, taste, and whether the powder causes digestive symptoms.

How much protein do I need in a calorie deficit?

The RDA of 0.8 g per kilogram is a minimum to prevent deficiency, not a target for retaining muscle. Helms 2014 reported that 2.3 to 3.1 g per kilogram of fat-free mass is associated with lean mass retention in athletes in a deficit. For someone training and eating less, 1.6 to 2.2 g per kilogram of body weight is a defensible range, and the exact point is not well resolved.

Is protein powder cheaper than chicken?

Per 20 g of protein, whey concentrate at 2024 UK prices costs about £0.50, skinless chicken breast about £0.83, eggs about £0.71, and dry red lentils about £0.14. Powder is cheaper than chicken and eggs but more expensive than lentils. It is a convenience purchase, not a cost-saving one.

Protein Powder: When It Helps and What It Costs

Protein powder is a convenience food. It is not a requirement, and it is not a category of nutrient. The useful question is not whether it is needed in the abstract, but whether it delivers grams of protein at a cost and in a form that fits the rest of the diet. That comparison is arithmetic, and it can be done with the same units used for any other food.

This page carries intake and weight figures. It is not medical advice. Anyone with a diagnosed eating disorder, or who suspects one, should not use these numbers to set a target; Beat, the UK eating disorder charity, runs a helpline on 0808 801 0677. Clinical conditions that affect protein requirements, kidney function or fluid balance are outside what a reference page can address.

The RDA is a minimum, not a goal

The Recommended Dietary Allowance for protein is 0.8 g per kilogram of body weight per day for adults. That figure comes from the Institute of Medicine’s 2005 report, and it was set to prevent nitrogen imbalance in healthy people, not to optimise body composition. It is a floor. It says nothing about what someone eating in a calorie deficit should do to retain muscle.

A target for someone in a deficit is a different number. The evidence here is less settled than the RDA. A 2014 meta-analysis by Helms and colleagues, published in the Journal of the International Society of Sports Nutrition, reviewed the literature on lean athletes in energy restriction and reported that 2.3 to 3.1 g per kilogram of fat-free mass per day is the range most consistently associated with retaining lean mass. That is fat-free mass, not total body weight, and the two diverge sharply in anyone carrying more fat. A 2018 review by Morton and colleagues in the British Journal of Sports Medicine, covering 49 trials, found that protein supplementation increased gains in resistance-trained people up to about 1.6 g per kilogram per day, with the confidence interval extending to 2.2. Above that, the additional benefit was not detectable in the pooled data. The honest summary is that somewhere between 1.6 and 2.2 g per kilogram of body weight is a defensible range for someone training and eating in a deficit, and that the exact point within it is not well resolved. Where the evidence stops being clear, this page says so rather than picking a number.

What a powder actually is

Whey and casein are the two protein fractions of milk. Whey is soluble and empties from the stomach quickly; casein clots and empties slowly. A 2009 study by Boirie and colleagues, using labelled leucine, found that whey produced a rapid, large rise in plasma amino acids and casein a slower, flatter one. What that changes is the shape of the amino acid curve over the hours after ingestion. What it does not change is total daily protein retention when the same total is eaten. A 2011 trial by Soop and colleagues, infusing amino acids at matched rates, found no difference in muscle protein synthesis between the two. Plant blends, usually pea and rice, are lower in methionine and higher in lysine; combining them brings the amino acid profile close to milk protein, and a 2019 trial by Lynch and colleagues found no difference in strength or lean mass gains over 12 weeks when total protein was matched. The practical difference between whey, casein and a plant blend is digestion rate, taste and price. It is not a difference in outcome when grams are held constant.

Cost per 20 g of protein

A powder is priced per gram of protein like any other food. The comparison below uses UK retail prices collected in 2024, rounded to the nearest penny, and standard composition figures from McCance and Widdowson’s The Composition of Foods, 7th edition. The condition column is the one that matters: the figure changes with the form of the food, because water, bone and skin change the protein density per pound spent.

Source	Protein per 100 g	Cost per 20 g protein	Condition that changes the figure
Whey concentrate powder	80 g	£0.50	Brand and tub size; 2 kg tubs are cheaper per gram than 500 g
Chicken breast, skinless	24 g	£0.83	Cooked weight is about 75% of raw; raw is cheaper per gram
Whole eggs	12.6 g	£0.71	Price per egg varies by 40% between caged and free-range
Red lentils, dry	25 g	£0.14	Dry weight; cooked weight is about 2.5 times dry
Semi-skimmed milk	3.4 g	£0.59	Volume; 20 g protein is about 590 ml

Lentils are the cheapest source per gram in this table, and they are also the slowest to eat and the highest in fibre. Milk is cheap per gram but requires drinking nearly 600 ml. Whey is competitive with eggs and cheaper than chicken. The comparison is not powder against food in general; it is powder against the specific foods it would replace in a given meal.

A worked calculation

A 70 kg adult eating 2,000 kcal per day wants to know whether a powder is necessary to reach 1.6 g per kilogram. The arithmetic is shown step by step so it can be repeated with other numbers.

Step 1: target protein
1.6 g/kg x 70 kg = 112 g per day

Step 2: protein from food, using McCance and Widdowson figures
Breakfast: 2 eggs (12.6 g each) = 25.2 g
Lunch: 150 g cooked chicken breast (24 g/100 g) = 36.0 g
Dinner: 200 g cooked red lentils (25 g/100 g dry, cooked weight x2.5) = 20.0 g
Snacks: 200 ml semi-skimmed milk (3.4 g/100 ml) = 6.8 g
Total from food = 88.0 g

Step 3: shortfall
112 g - 88 g = 24 g

Step 4: powder needed
24 g / 0.80 g protein per g powder = 30 g powder

Step 5: cost of that powder
30 g x £0.025 per g = £0.75 per day

The shortfall is 24 g, which is one scoop. If the same 24 g came from chicken, it would cost about £1.00; from eggs, about £0.85; from lentils, about £0.17. The powder is not the cheapest option, but it is the one that requires no cooking and adds no fibre. That is the entire case for it.

What people get wrong

The most common error is treating the RDA as a target. The 0.8 g per kilogram figure was set to prevent deficiency, and it appears on food labels as a Daily Value. Someone who reads 50 g on a label and eats 50 g of protein per day has met the RDA for a 62.5 kg adult and may still be short of a muscle-sparing target if they are in a deficit. The mistake is natural because the RDA is the only protein number most people ever see, and it is presented without its purpose.

The second error is assuming that whey is superior to casein or plant protein. The digestion-rate difference is real and measurable in plasma amino acid curves. It does not translate into different outcomes when total daily protein is matched, and the trials that matched it found no difference. The third error is pricing powder against nothing. A powder is only worth buying if it replaces a food that would otherwise be eaten, or fills a gap that would otherwise be unfilled. Priced against lentils, it is expensive. Priced against a missed meal, it is cheap.

Where the evidence is thin

The range for protein in a deficit, 1.6 to 2.2 g per kilogram, comes from trials in trained people, mostly young and mostly male. Extrapolating it to older adults, to people with obesity, or to people eating very low calorie diets is not supported by the same data. The Morton review’s upper confidence interval of 2.2 g per kilogram is not a target; it is the edge of what the pooled data could detect. Above that, the trials were underpowered to show a difference, which is not the same as showing no difference. A figure that cannot be tied to a named trial or a stated range does not belong in a plan.

Protein powder is a convenience food with a known composition, a known cost per gram, and no mechanism that food lacks. It is useful when it closes a gap that food does not close, and unnecessary when it does not.

Protein Powder: Grams, Cost, and Whether It Is Needed