These handy snacks can add an average 20g to your daily protein goal – but experts have a word of caution for over-zealous bar munchers

It is best to raise your protein intake from a variety of sources, and your diet should then be healthier for it, not only because you’re aiding muscle growth, but because protein also helps reduce body fat and boosts your immune system. However, if you find yourself regularly consuming protein bars or protein heavy products, check your daily grams – you might be overdoing it. ‘Although the European Food Safety Authority (EFSA) says that there is no upper limit for healthy adults in terms of protein intake, there is also only so much your body can use,’ says registered dietitian Duane Mellor. ‘Any extra will end up being broken down to make sugars or fats. These will either then be used as a source of energy to fuel your workout, or converted to be stored as fat.’

You need to make sure that any extra calories, even if eaten in the form of protein, aren’t turning against you by creating fat deposits – if you get this right, protein bars can be a helpful addition to a healthy, muscle building lifestyle. ‘It’s best to try to get your basic diet as balanced as possible using a “food first” approach,’ says Mellor. ‘However, this is not always practical in a modern and busy world. Fitting healthy eating around working hours and exercise can be a little tricky. Protein bars can be healthy, but perhaps the key thing to remember is just because a bar is labelled protein, it doesn’t guarantee that it’s a healthy product.’

Getting the balance

It might be tempting to load your performance-boosting schedule with sensationalised treats that look like they’re going to give you super-human strength – but you’re better off mastering a nutritional balance. Your average protein bar contains as much protein as half a cod fillet – about 20g. The experts say this is enough to stimulate muscle growth, but one British study found that the ideal amount to consume after a workout is 40g (or 0.4g per kg of you).

Does this mean that smashing two protein bars after every gym sesh fills the protein void? Experts say this is ill-advised, as you could be overdoing it on other ingredients that help give snacks taste and texture, such as inverted sugars (a mix of fructose and sucrose). ‘You’re unlikely to need more than one bar’s worth of extra protein per day,’ says Mellor. ‘Those who exercise regularly should have around 1.4g of protein per kg of bodyweight a day. The main problem is if you’re eating too many protein bars, you might over-fuel with too many calories. If you’re healthy, your kidneys and liver will unlikely be affected, but you might not gain any more muscle and risk gaining a little fat.’

The main ingredients

• Whey

The most common protein powder is whey, a by-product of cheese that’s high in protein and low in fat. ‘Whey protein is made from the liquid left over from making cheese,’ says Mellor. ‘It is a complete protein containing all the essential amino acids and there’s evidence it can help support weight loss and help maintain lean mass.’ Due to high demand for whey, prices are soaring, so manufacturers are using less expensive protein types such as soy concentrate. Look out for whey isolate for the best quality protein: it’s more processed than whey concentrate but this means it contains less carbs, less fat and more protein content. Try PhD Birthday Cake Smart Bar (£2.49, 60g ), and Grenade Caramel Chaos (£2.49, 60g).

• Plant-based

Soy bean powders contain fewer amino acids than whey (you need a full matrix of amino acids for muscles to grow efficiently), but are a great source of plant-based protein. One study found that soy protein helps lower LDL (‘bad’) cholesterol by 3-4%. ‘The evidence suggests soy protein contributes to heart health,’ says Dr Jenkins, lead study author, although this is not yet an agreed health claim. Other plant proteins include rice protein and pea protein, often mixed together as a complete amino acid matrix. Try Pulsin Mint Choc Chip Protein Booster (£1.89, 50g)

• Casein

This powder makes up 80% of the protein in milk, the remaining 20% being whey. It’s also a by-product of cheese, but very different to whey in terms of benefits. Experts recommend both for a muscle building diet: whey has more of the branched-chain amino acids – leucine, isoleucine and valine – thought to decrease muscle fatigue; casein is easier to digest and helps release protein slowly, so muscles have a steady supply of recovery fuel. Try Grenade Reload Flapjack Chocolate Brownie (£1.59, 70g). All products hollandandbarrett.com.

Bars vs Shakes

Where shakes were once king, bars have now taken over the nutrition market. But don’t chuck your trusty shaker in the bin, as they both have their place in the world of wellbeing. ‘It’s always best to base your diet on food, but where that isn’t possible, a shake can be helpful as it may contain less fat than a bar – but you still need to look out for sugar,’ says Mellor. ‘Think about which is easiest to carry with you for a post-workout snack.’ Solid-form protein makes you feel fuller, and suppresses hunger for longer, found a study from the Netherlands. But experts from the USA found that protein in a liquid form delivers amino acids to your bloodstream more efficiently, and ultimately makes the most of your recovery window, making shakes the better choice for a post-workout snack. Choose which works for your lifestyle, but ultimately ensure that you’re getting the bulk of your nutrition from breakfast, lunch and dinner.