New study reveals protein bars offer less digestible protein and may harm your health.

Protein bars, often touted as the effortless way to boost muscle growth, are under fire after a shocking new study revealed most deliver far less usable protein than claimed — and may even pose serious health risks.

For many gym newcomers, protein bars seem like a godsend. When starting weight training, the so-called ‘newbie gains’ phase offers rapid muscle growth, which hinges on meeting daily protein targets. Experts advise consuming between 1.2 and 2 grams of protein per kilogram of body weight to fuel this progress. Traditionally, this comes from foods like chicken, fish, eggs, and steak, but protein bars promise a quick fix with around 20-25 grams per serving.

However, the reality is far from straightforward. Researchers analysed 1,641 protein bars from the database OpenFoodFacts.org, scrutinising their protein content, source, and nutritional quality. Their findings are alarming: 81 percent of bars marketed as ‘high protein’ actually offer only about 47 percent of their protein in a form the body can digest. This means if a bar claims 20 grams of protein, fewer than 10 grams might be biologically usable.

The culprit, scientists explain, is often the type of protein used. Many bars rely on lower-quality proteins like collagen, combined with fillers such as carbohydrates, fats, and fibres, all of which reduce the bioavailability of essential amino acids necessary for muscle repair and growth.

Experts caution that protein bars are supplements—not substitutes for whole foods. “They should be consumed as part of a complete diet,” the study emphasises. Relying on bars instead of balanced meals could shortchange your body’s protein needs and impair muscle development.

Adding to the concern is the ultra-processed nature of many protein bars. According to the NHS, ultra-processed foods are industrial formulations mostly created from extracted or synthetic ingredients like hydrogenated fats, modified starch, artificial flavourings, and additives designed to make products hyper-palatable. Such diets have been linked to a slew of health problems, including obesity, type 2 diabetes, heart disease, and even bowel cancer.

The NHS also notes it’s unclear whether these health risks stem from the processing itself or from the high levels of calories, fat, salt, and sugar commonly found in ultra-processed foods. While some processed foods—like wholemeal bread or high-fibre cereals—can fit into a healthy diet, frequent consumption of highly processed protein bars might carry hidden dangers.

This study sends a strong warning signal to fitness enthusiasts and casual consumers alike. The convenience of grabbing a protein bar on the go masks a disappointing truth: most protein bars won’t give your muscles what they need, and regular use could increase your risk of chronic health issues.

In a fitness culture increasingly reliant on quick fixes, the temptation to replace home-cooked meals with protein bars is understandable. But experts urge a return to whole-food nutrition and using bars strictly as a supplement, not a meal replacement.

Ultimately, building muscle demands more than convenience—it requires quality nutrition. This study reminds us that not all protein bars are created equal, and many fall drastically short of the promises on their packaging.