Protein! It’s never been bigger. Half-ignored for years as the macronutrient that only weightlifters and bodybuilders needed to worry about, the general public’s nutritional know-how has finally caught up to the idea that it both fills you up – helping you eat less sugary, over-processed stodge – and provides vital nutrition for a healthy body.
But with nutritionists, doctors and diet books providing wildly fluctuating estimates as to how much you should actually be aiming to eat, who’s got it right?
The nuanced news is, there’s no one-size-fits-all recommendation. The good news is, it’s easy to work out a sensible daily intake. Here’s how...
What is protein?
Here's the 10-second science: Proteins are organic molecules made up of amino acids, otherwise known as the building blocks of life. Your body can make some of these amino acids naturally, but needs to get others from food – that’s why they’re known as ‘essential’ (incidentally, omnivores find it easier to get their daily hit than vegans – meat, chicken, eggs, dairy and fish contain the full set of nine amino acids, while plant-based protein sources might only include a few).
Eat some scrambled eggs, for example, and your body breaks down the protein into amino acids, then uses them to build or repair everything from muscle to organs and hair – but also uses them to produce enzymes, hormones, neurotransmitters and antibodies.
As you’re probably already aware, it’s possible to function pretty well on a low or even no-carb diet, and cutting fat isn’t always an issue – but without enough protein, your body won’t function well at all.
Is it possible to eat too much protein?
In the UK and US, the recommended daily intake of protein for men is roughly 0.8g per kilo of bodyweight, or around 55g for the average man. As for an upper limit, the World Health Organization (WHO) sets a safe level of protein at 0.83 g per kilo of bodyweight per day, which they say 'is expected to meet the protein needs of 97.5% of the world’s healthy adult population.'
That’s certainly enough to prevent protein deficiency, but it’s probably not ideal – older people function better on more, and so do high-performing athletes.
One large-scale review of studies showed that taking in up to 1.6g per kilo of bodyweight produced extra gains in lean body mass from resistance training, while some trainers suggest that up to 2g might be the magic number. This is partly because intense exercise burns amino acids for fuel, but also because strenuous activity causes increased breakdown of proteins in the body.
There’s also unlikely to be a downside of upping your intake – at least, to a reasonable point.
You might have heard that excess protein intake can damage your kidneys, but the science doesn’t back that up – the only study where too much caused problems was conducted on people with pre-existing kidney conditions, while a study on lifters with protein intakes of 2.8g/kg of bodyweight per day showed no significant differences in kidney function from athletes on a more moderate intake.
Several studies have found positive connections between protein intake and bone mineral density, and there’s some evidence that replacing some carbohydrates with protein might decrease the risk of heart disease by improving your levels of ‘good’ HDL cholesterol.
Protein also makes you feel more full and has a mild thermic effect – digesting it actually burns calories – in comparison with carbs and fats.
When's the best time to eat protein?
For years, it’s been assumed that you should spread your protein intake throughout the day, based on a couple of questionable studies that seemed to suggest that the body could only absorb 30g at a time.
But there’s a catch: '[those] findings are specific to the provision of fast-digesting proteins without the addition of other macronutrients,' notes researcher Brad Schoenfeld in a review published in the Journal of the International Society of Sports Nutrition.
'Based on the current evidence,' Schoenfeld says, 'we conclude that to maximize anabolism one should consume protein at a target intake of 0.4g/kg/meal across a minimum of four meals in order to reach a minimum of 1.6g/kg/day.'
How much protein should you eat? Conclusion
The bare minimum proitein intake you should aim for is 55g – you could cover that with eggs for breakfast and legumes for lunch – but a bit more won’t hurt, and will probably help, especially if you’re lifting weights or doing any kind of strength training.
You should try to get a hit of proteing with every meal. You can also make some easy swaps. If you’re snacking on sweet things, for example, consider swapping chocolate for Greek yoghurt. Fancy a savoury snack? Go for nuts over crisps. You’ll curb cravings, help your body repair itself, and possibly get leaner in the process.