The art and science of snacking on protein bars

They look tasty, but what are protein bars actually made of? And when’s the best time to munch one? We asked London-based nutritionist Clarissa Lenherr to debunk the myths surrounding your favourite snack.  

By Team Cosmo
21 January, 2023
The art and science of snacking on protein bars

Protein bars may be quick snacks and easy to carry but if you're just starting out, it can seem a little daunting, given the varieties available. And then again, everyone gives you different advice. So once and for all, here's everything you need to know about protein bars.

If I eat a protein bar every day, will I get bulging biceps? 

Not exactly, says Clarissa. She advises against eating them daily but adds that protein is needed for building muscle (alongside strength training workouts). “Our diets should be as diverse as possible, with macronutrients coming from a variety of food sources,” she notes, stressing the importance of whole foods (such as eggs, vegetables, fruits, nuts, grains, and legumes). “But if protein bars are one of the only ways you can fit in a protein source, they can be a good addition to your daily intake.” Don’t overdo it: Clarissa advises that high amounts of protein can put stress on the kidneys. “Aim for roughly 0.8g to 1g of protein per day, per kg of body weight.”

Can a protein bar replace a meal?

It’s always preferable to eat a healthy, balanced diet when you can, rather than regularly relying on substitute snacks. Plus, there are so many types of bars that it can get confusing. Energy bars contain high-calorie ingredients that deliver fuel to keep you going through the day; protein bars are intended as a pre or post-workout supplement to offer additional protein, and meal replacement bars are a combination of both (not intended as a substitute for regular meals but used if you are time poor). Back to protein bars: Clarissa says it is actually better to eat little bits of protein throughout the day, rather than bulking up via one meal alone (top tip: chicken, yoghurt, lentils, and fish are all great sources if you are getting your cook on!). But a protein bar can be a great way to get a little boost in, especially if you are out and about.

When exactly should you eat a protein bar? Ever heard that you need to eat protein immediately after your workout, otherwise it won’t ‘count’?

That’s not strictly true, but there is an optimal window, as Clarissa reveals. “There’s a time frame of around four hours post-working out in which our muscles are most receptive to protein,” she explains. “Aim to eat your protein bar one to two hours post-exercise.” Scoffing one prior to exercising can be beneficial. “Make sure to give yourself an hour to digest, more if it is a high-fibre protein bar. Fibre takes longer to break down; no one wants a protein bar sat in their stomach while they are working out.”


Know your ingredients

It’s a good idea to understand what’s in your food. Here are some common additions, decoded. 

Inulin: A type of soluble fibre that works to support gut health, it’s added to bars to act as a binder and natural sweetener. But be mindful that too much can cause an upset stomach. 

Xylitol, Sorbitol, Maltitol: Avoid bars with too many of these sugar alcohols, aka polyols. They can upset your stomach and cause a laxative effect. This is especially important to note if you have IBS (Irritable bowel syndrome).

Carrageenan: This seaweed derivative, used as an emulsifier, has been known to cause intestinal irritation. Always check the label for it if you suspect that it’s a problem for you. 

PS: Look for a bar with whey and pea proteins, with at least 3g fibre per serving. Avoid if sugar, high-fructose corn syrup or sucrose is the main ingredient.