Protein. How an essential nutrient became a diet fad.
Something akin to protein MANIA seems to have taken hold of our journalists and food marketers. Suddenly, everything seems to have been imbued with this supposedly miracle-giving macronutrient. From chocolate bars, to smoothies, to products that we’d expect to contain protein as standard (‘protein milk’ anyone?), pretty much every blinking snack out there seems to have been boosted with the big P. And that’s before we even get to all the protein powders weighing down the shelves in supermarkets and health food stores across the country.
What’s going on?
Well, my chief suspicion here is that in high income countries such as Britain, widespread neurotic attitudes around diets and eating, combined with a long history of mixed messaging about nutrition has led to our current obsession with protein. Fat has too many negative connotations for our diet culture to be able to effectively sell us the benefits, and the low fat vs. high fat debate still rumbles on, confusing many. The carbohydrate group meanwhile, is still in rehab, after the long-lasting campaign of fear-mongering and suspicion waged against it.
Of the three macronutrients, that leaves us only with protein. Perhaps no surprise then, that marketers have seized on protein as the healthy, ‘guilt-free’, nutrient du jour.
Add into this the fact that whey protein – commonly used to add protein to products - is as cheap as chips, and you can see why food manufacturers are so keen to integrate it into so many products while charging you a bit extra for the associated ‘halo effect’. The protein supplements market has risen by 27% since 2014, and UK consumers spent £66 million on sports nutrition food and drink products in 2015 with this figure projected to rise.
But what actually is protein?
Alongside carbohydrates and fats, protein is the third essential nutrient we need in sizeable amounts for energy and growth. Protein plays a key role in growth and maintenance of all the cells in our body, providing structure for our muscles and cellular membranes, and essential for the synthesis of hormones and enzymes.
This macronutrient actually consists of amino acids, the building blocks of what we call ‘protein’. There are 21 of these little building blocks, all doing different things, of which there are 9 we can only obtain from the diet. These we call the ‘essential’ or ‘indispensable’ amino acids. The other 11 amino acids are made in some quantity by our bodies. So our bodies are constantly breaking down proteins into these constituent parts, and then reassembling them depending on what protein the body needs and where. This process of protein turnover is delicately balanced, and is perhaps the original example of a recycling efficient enterprise.
Interestingly, protein is the odd one out of the macronutrient group, and isn’t stored in any significant quantity in the body outside of our muscles. We excrete any protein we don’t need in the form of nitrogen, carbon dioxide, and urea (yep, you guessed – most unnecessary protein exits your body via pee).
And how much do we need?
Of all three of the macronutrients, we actually need protein in relatively small amounts compared to carbohydrates and fats, given how efficient our bodies are at recycling here. Typically, 10-15% of our total daily energy needs should come from protein, which translates as 0.75 grams per kg of bodyweight.
For an average sized woman that comes to roughly 55g of protein a day, which is only about the size of two chicken breasts or a smallish steak.
Although we don’t know exactly what the safe upper limit of protein is to consume each day, there is evidence to suggest that more than 3-4 times the recommended daily amount (RDA) not only has no proven benefit, it also can’t be judged to be completely safe. Intakes where 45% or more of your total daily energy needs come from protein can even have a toxic effect. Somewhat bizarrely, protein toxicity is also known as ‘rabbit starvation’ – due to the fact its side effects were first noticed amongst Artic explorers existing mostly on rabbit meat. Toxicity aside, let’s not forget that as with any macronutrient, eating too much in excess can lead to weight gain.
Although protein is certainly more satiating than other foods, which can help us feel fuller for longer, you should by no means think of protein as your ‘get out of jail free card’ when it comes to overeating. Animal proteins for example, aren’t just pure protein, but a mixture of fat, water, sodium (salt), vitamins and minerals and protein. One hundred grams of chicken for example, gives you 24g of protein, and 76g of water and other nutrients and compounds not all of which we should eat to excess.
Are you sure? Shouldn’t I eat more for strength and to get muscly?
There’s relatively little evidence to suggest that protein can build muscle without individuals also taking part in resistance training such as weight lifting. Our bodies are constantly battling to maintain balance – a process known as homeostasis. This means that we maintain a state of nitrogen balance, excreting out via our faeces, skin and urine the same amount of nitrogen that we take in from food.
There’s even a school of thought that something called ‘adaptive demand’, means your body loses amino acids at a rate that depends on what your usual protein intake is. In other words, the body’s protein demands are variable, but always need to be in balance. So only a sustained increase in protein intake over a long period of time will eventually result in your metabolism changing to more closely match levels of intake.
Although bodybuilders are recommended to consumer more protein than your ordinary civilian, it’s still not a huge amount more than the standard recommendations, at up to 1.2g/kg of bodyweight.
Some closing words
While we absolutely need protein for a healthy diet and lifestyle, and there is plenty of evidence to suggest protein can help with weight loss by promoting feelings of fullness, it should form part of your daily diet only in balance with the other nutrients.
So there’s no need to go overboard. Chicken every night is hardly the most environmentally friendly diet out there (protein can also be found in many plant based products, such as legumes, in lower amounts). That protein packed chocolate bar may well be high in protein, but will still contain sugar and fat, and potentially contribute to weight gain in exactly the same way eating too many non-protein boosted chocolate bars can. And buying large tubs of protein powder probably has more of an impact on your wallet than it does on your body.
As with most things nutrition, the message is the same. Enjoy, in moderation.
References
Millward D Joe, Protein Requirements. In Human Nutrition (13th ed.). 2017 OUP, Oxford. Pp.196-215.
https://www.ncbi.nlm.nih.gov/pubmed/15466943
www.NHDmag.com November 2017 - Issue 129, sports nutrition case study