How much protein is the right amount in your regular diet and as a supplement after a workout? Our understanding of how our bodies use protein is evolving, so let’s take a look at the latest science to help you decide on the best approach when it comes to planning your diet and deciding which supplements to use.
Protein supplements are designed to help your body build muscle tissue by fuelling a process known as muscle protein synthesis, or MPS.
When you do a resistance exercise like lifting weights the fibres in the muscles are damaged. This is perfectly normal, because MPS is the process by which those fibres grow bigger and stronger when they repair themselves.
The key building block in this process is protein, so without enough in your diet you will not see the benefits of your exercise.
Everybody needs protein just to live, and how much protein you need per day will depend on your body type and levels of physical activity. It could be as low as 1.2g per kilogram of body weight for someone who is fairly inactive, but as much as 3.3 g/kg for an active person trying to gain muscle mass.
This is where supplements come in, as you can top up your diet with a post-workout shake or bar to ensure the MPS process has all the protein it needs.
A Scottish study in 2016 overturned the general view that 20g of whey protein after a workout was the ideal amount. It showed that subjects responded better to a 40g dose of protein than a 20g dose, regardless of their lean body mass.
Your gut absorbs protein into your blood, so it can be transported to the muscles. It will pass through the liver, and any unused protein is simply removed by the kidneys and passed out in your urine.
So far as we know, your kidneys and liver can cope quite well with a high-protein diet, as long as you don’t have any existing problems with these organs.
However, some studies have found evidence that rapidly increasing your protein intake could cause liver or kidney problems as they adjust to the new load. If you want to use more, it makes sense to increase your levels slowly.
When it comes to losing weight, you should remember that no supplement is going to be a magic bullet. A healthy diet and plenty of sensible exercise are the absolute bedrock of any weight loss plan, but protein supplements can help.
A Canadian study found that its overweight subjects could lose weight while adding lean muscle mass by using a protein supplement, but it’s worth noting that they also cut their calorie intake and undertook a rigorous exercise regime.
As with losing weight, staying healthy in general is very rarely about avoiding or using one supplement. Protein provides your body with a hormone called IGF-1, which encourages cell growth.
Your muscles use it to grow, so it’s a very important part of your diet, but cancerous cells also use it grow. Studies which show a link between a high protein diet and diseases like diabetes and cancer usually also find that the protein sources involved are low-quality processed meat.
If you eat healthy food in general and exercise regularly, then a high-protein diet is unlikely to cause you long-term health problems.
If you have diabetes then you should consult your doctor before increasing your protein intake. This is mainly because diabetes often causes damage to the kidneys, which are essential for removing both excess protein and the normally harmless by-products of MPS.
Diabetics also need to be aware that the body can break down protein into glucose as an energy source, just like it does with carbohydrates. It does this more slowly for protein, so the effects are not as immediate but can cause problems if you have diabetes.
Anyone who is thinking about how much protein they need in their diet will find different answers depending on their fitness goals and personal circumstances. Take particular care if you have diabetes or any other kidney-related health issues and always consult your personal trainer or doctor if you are unsure.