What your ‘healthy’ protein bar is really doing to your body
Protein repairs and builds tissue, reduces hunger and may even help with weight loss. Add the magic phrase “high-protein” to the packaging of bread or yogurt – or even ice cream and Snickers bars – and suddenly they wear a health halo.
The global protein bar market is projected to grow from ￡3.71 billion in 2022 to ￡5.60 billion by 2029, according to Fortune Business Insights. Once niche products sold in health food shops to athletes and bodybuilders, they are now available everywhere, in supermarkets, convenience stores, even Poundland.
They can contain around 20 grams (about three quarters of an ounce) of protein, providing about a third of the recommended daily protein intake for an average sized person in the UK.
But while they pack a protein punch, most are also high in calories and many are high in unhealthy saturated fats. Most are also classed as ultra-processed foods.
Studies into their health benefits are limited. Naveed Sattar, a professor of cardiometabolic medicine at Glasgow University’s School of Cardiovascular and Metabolic Health, says: “There is lots of good evidence that protein suppresses appetite. But the question of whether protein bars are health-giving in and of themselves has not been trialled yet.”
Rob Hobson, a sports nutritionist and the author of Unprocess Your Life, adds: “People are obsessed with protein, but they confuse ‘high protein’ with ‘healthy’ because they think protein is the most important nutrient to get in your diet.”
He describes many protein bars as a “mishmash of weird ingredients, bindings, sweeteners and emulsifiers, which some studies suggest negatively affect gut biome. They are an ultra-processed food, whatever way you look at it.”
Common ingredients include maltitol, a sweetener that can cause diarrhoea, whey protein, which can cause bloating, sucralose, which can impact on the variety of gut bacteria, and inulin, which is a fibre source that can lead to bloating.
The few studies into protein bars show mixed results. One study by researchers at Arizona State University published last year in the Journal of Functional Foods concluded that daily ingestion of protein bars can “significantly” increase fat mass. A 2021 study of elite athletes concluded that consumption of protein bars improved the athletes’ “physiological adaptation after training”.
Meanwhile, a 2006 study compared the effects that high protein and high fibre bars had on glucose and insulin levels in a cohort of 23 women, and found that glucose and insulin responses – and peak glucose levels – were significantly lower in those who ate bars high in protein and fibre compared with women who had eaten bars high in fat and sugar. A morning high-protein bar also reduced energy intake at lunch by 5 per cent.
Priya Tew, specialist dietitian from Dietitian UK, says that, generally, most of us get enough protein from our regular diets, and recommends against relying on ultra-processed snacks, which most top-selling protein bars are.
“We all need protein in our diets; it is a very important macronutrient, but so are carbohydrates and fats. The key is not to focus on just one nutrient or food group but to aim for balance. The average person is not going to need protein bars daily, but this does not mean that all protein bars need to be excluded, or that all of them are equally nutritious.”
Nine protein bars ranked by taste and health benefits
Grenade Oreo 60g bar
21g of protein, 1g sugar, 233 calories
Taste: Generically sweet and chewy
Health benefits: The high protein content of the top-selling bar on Amazon is overshadowed by high calories, high saturated fat (more than a Mars Bar) and a mishmash of synthetic sweeteners, bulking agents and emulsifiers, plus the addition of bovine collagen. “Which is basically made from the tendons and other bits of cows,” says Hobson.
Fulfil chocolate salted caramel vitamin and protein 55g bar
20g protein, 1.4g sugar, 205cals
Taste: The addition of crunchy pieces brings texture to the underlying sickly chew.
Health benefits: Full of sweeteners, emulsifiers and synthetic ingredients, including hydrolysed collagen, the bar provides around a third of the recommended daily protein intake for an average sized person in the UK. Nutritionists advise that people should aim for around 0.8g of protein per kilo of body weight.
This means an average 85kg (13st 5lb) British man should aim to eat 68g of protein a day, while an average 72kg woman should aim for around 58g. For comparison, a medium sized cooked chicken breast contains around 54g of protein, while a hard-boiled egg contains 6g. The addition of vitamins and 2.6g of fibre to this bar also adds some nutritional value.
ON Optimum Nutrition chocolate sea salt crunch 55g bar
18g protein, 1.9g sugar, 221cals
Taste: Unpleasant chemical aftertaste, like burning tyres.
No stars
Health benefits: This is high in saturated fat, high in calorie content and contains 16g of polyols, which are sugar alcohols. It is recommended that no more than 10-15g of polyols should be consumed per day, to avoid digestive issues. Food labelling guidance also states that any food containing more than 10 per cent added polyols should state “excessive consumption may produce laxative effects”, which the packaging does.
PhD smart plant vanilla fudge 64g bar
21g protein, 0.6g sugar, 249cals
Taste: Floury and crumbly, with crunchy pieces, overlaid on a generic sweet firm paste with no discernible flavours.
Health benefits: It has plant derived proteins but is still high in saturated fat, with 16g of polyols. For a snack, the bar is also excessively high in calories, as Prof Sattar explains: “One protein bar is a lot of calories for a snack. The ideal snack is something like a banana at 90 calories or an apple at 50 calories.”
He recommends cutting bars into halves or thirds.
PE The Bar cookies and cream, 60g
21g protein, 1.3g sugar, 193cals
Taste: Barely benefits from an added layer of caramel-type gloop.
Health benefits: This is low in saturated fat, low in sugar and has 4.3g of fibre, but is high in polyols.
Barebells cookies and cream 55g bar
20g protein, sugar 1.4g, 190cals
Taste: Less offensive than others – not as sweet or sickly – with added crunch.
Health benefits: It is still a UPF but with more recognisable ingredients and fewer of them, including maize fibre, milk powder and potato starch. It also contains 3.5g of fibre.
Trek protein cocoa oat flapjack, 50g
9g protein, sugar 14g, 227cals
Taste: Biscuity and oaty.
Health benefits: This is oat-based and provides a more balanced nutritional matrix than most UPF bars, with higher protein content. It’s high in sugar and calories but with more natural, recognisable ingredients.
Pulsin chocolate fudge peanut keto bar, 50g
12.6g protein, 1.9g sugar, 247cals
Taste: It has real peanuts, is not overly sweet, and is crumbly.
Health benefits: It is a mix of medium-chain triglyceride (MCT) oil and peanuts. MCTs are used as fuel in the body and are absorbed into the bloodstream and converted into energy easily. The bar is high in saturated fats but with 9.3g of fibre and a low 1.9g of sugar.
Nakd cocoa hazelnut bar, 45g
7g protein, 11g sugar, 190cals
Taste: Recognisable flavours of dates and peanuts; not overly sweet.
Health benefits: This has a low 1.6g of saturated fat, and 6.9g of fibre. While high in sugar at 11g per bar, the sugars are all naturally occurring from the limited ingredients of dates, peanuts, chicory fibre, peanut flour, hazelnuts, fat-reduced cocoa powder and natural flavourings.
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