Real Voices interview: Martin MacDonald

A clinical performance nutritionist talks about training athletes and why its important to have protein in your diet

What do you do?

I provide nutrition support to the Great Britain weightlifting team and the Paralympic powerlifting team. I also work with some professional football teams and individual clients, who might be student athletes or just people who want to be healthier.

How much protein do weightlifters need?

Their protein intake is based on their body weight – approximately two times their body weight (measured in kilograms) in grams of protein per day. If they weigh 70 kg, that’s 140 g of protein a day.

What about ordinary people?

The government RDA [recommended daily amount] of protein is set very low, at a level just above protein malnutrition: 0.8 times your body weight (in kg) grams of protein. Most nutritionists would probably give them quite a lot more – I’ll rarely use less than 1.5 grams protein per kilogram in body weight.

Which foods do weightlifters get protein from?

The main sources of protein we use are animal sources: eggs, milk, cheese and any kind of meat or fish. We use whey protein (which comes from milk) sometimes; if they want to have porridge for breakfast, there’s not a lot of protein in that, so we’ll get them to add a scoop of whey protein. We sometimes use offal, if they like the taste – things like liver, kidney or even heart.

Why do weightlifters need protein?

Weightlifters need protein for the same reason everyone else does, which is to maintain the function of the body. Weightlifters especially need protein because when you train with heavy weights, there’s a certain amount of muscle damage, and protein promotes recovery and adaptation to that training stimulus. Something between 20 and 30 g of protein per meal maximally stimulates protein synthesis. This allows them to recover from training and minimise injury.

What about other food groups?

Fat is really important for maintaining people’s immune function, helping them recover from exercise by helping to produce hormones, so I keep fat at 25 to 40 per cent of their diet. Carbohydrate is very important for intense training, so the carbohydrate changes with the amount of training they do. If they do more sessions a day, they’ll eat more carbohydrate.

Does the recommendation differ between weightlifters and powerlifters?

Yes, to some extent. The nutrition support for the Paralympic powerlifters is slightly different because you have to tailor it very much around any clinical issues that they have. If someone’s paralysed below the waist, for example, there’s no muscle activity in their legs and you have to reduce their food intake. This is tricky because their stomach is still the same size and people like to fill their stomachs to feel full. We use lots of vegetables and salad to increase the bulk of meals, and not as much carbohydrate as it can make inactive people hungry.

How do weightlifters get to the correct weight?

If the weightlifters’ natural weight is a little bit higher than their weight class, then we reduce it at competition time, mainly with calorie restriction. We give them lots of vegetables and increase their protein intake slightly because protein keeps you full and speeds up your metabolism (see this paper).

We also sometimes use a low-residue (low-fibre) diet a few days before competition. Fibre goes into your intestine, then when you go to the toilet it goes out again. So on a low-fibre diet, when the person goes to the toilet, they lose weight but they don’t add that weight back on. This diet involves switching to white rice, very low-fibre fruit and vegetables, and lots of meat and dairy (which don’t contain fibre).

What’s the best way for ordinary people to lose weight?

Our way isn’t necessarily the best way for the general population because we’re trying to lose a little bit of weight in the short term. What you’re trying to do when you lose weight (for most of the general public) is lose body fat, so lots of people do a low-fat diet. But actually, if you start eating all low-fat products, the food suddenly doesn’t taste very good so people start adding sugar, which is not good for weight loss. Lots of people find eating a lower carbohydrate diet easier to stick to. I’ve got a saying, “The best diet is the diet that suits the person best”, so if you can stick to it, that will work better than anything fancy.

How much are your recommendations based on scientific research?

I’d probably say they are 80–90 per cent based on scientific research. If you were to be 100 per cent evidence-based you would only use what’s completely proven, but then you’re always one step behind someone else.

Are sports drinks helpful?

It depends somewhat on what you’re defining as a sports drink. We use electrolyte drinks (which are mainly water, with some different salts and no sugar) quite a lot for rehydration. But a sports drink like Lucozade Sport that has lots of sugar in it would be relatively pointless the majority of the time for a weightlifter because they’re not doing that kind of exercise. You need sugar for high-intensity activities – so having a sports drink during a football match or long-distance running event can improve your performance. The problem is people who don’t need sports drinks having them: going for a 30-minute run and having a sports drink is a terrible idea, especially if your goal is weight loss, because they contain so much sugar.

How did you become a nutritionist?

I have A levels in sports studies and biology. I then did my degree at Loughborough University and a Master’s in sports and exercise nutrition. I think most of my knowledge has come from trying out nutrition strategies on myself and while at university reading internet forums on nutrition to see what people are doing in real life. I set myself up as a self-employed nutritionist straight away and started working with anyone and everyone who wanted to work with me, and five years later have a successful consultancy.

What is the best bit of your job?

You’re able to change someone’s life through nutrition. With sportspeople you can get them to win a medal, but it’s more rewarding to change the life of a non-athlete through healthier eating. For example, the doctor might tell someone that they have to go on medication to avoid type 2 diabetes, but you can prevent them needing to take drugs with proper nutrition.

Further reading

About this resource

This resource was first published in ‘Proteins’ in January 2014.

Topics:
Physiology, Cell biology, Immunology
Issue:
Proteins
Education levels:
16–19, Continuing professional development