Round-up: live Q&A with Martin MacDonald

Sports nutrition expert talks ideal racing weight, cutting sugar intake and more

Martin MacDonald

Here are some of the highlights…


Helen Webster: Every time I lose the last stubborn 1/2 stone that I think gets me to my ideal ‘racing weight’ I seem to get ill with colds, coughs etc. Any ideas why?

Martin MacDonald: Hi Helen! This is an interesting one that could bring up lots of questions. You’ve already somewhat hinted at one of the questions… what makes you think its your ideal race weight?

The first two nutritional points that spring to mind are firstly, speed of weight loss and therefore the energy deficit that you are creating and secondly, your macro/micronutrient intake during this period of energy deficit.

Low energy intake can have a profound hormonal, metabolic and immune function impact. Similarly, low intakes of certain macro and micronutrients can reduce immune function. The one that we see very often in endurance athletes is a reduction of foods that are deemed to be ‘high fat’. The reduction of fat can impair immune function as well as the reduction in the foods lowering intakes of important minerals, especially zinc, which may again be an issue.

Lowering fat intake can also unfortunately lead to a reduced protein intake if you are not careful which again could be a factor. 

Interestingly, it could just be a coincidence, you may reach a state of over reaching/training at the same time that you usually try to drop half a stone and at this time you are immuno-compromised anyway.

If any of those seem like they could be on point, feel free to ask and I can expand further.

Alasdair-G: Should I give up my glass of fruit juice in the morning? I am concerned about the level of sugar in my diet and see it as a way of reducing my intake.

Martin MacDonald: This is one of those current topics that I mentioned that would be interesting to discuss! The answer is… it depends. If you were ‘asymptomatic’ for any issues that drinking that fruit juice might cause, there isn’t really a necessity to get rid of it.

However, if you are trying to improve body composition, or were suffering with gout for instance, there could be an argument for decreasing your intake.

Is there a reason you’d want to cut it out? Other than worrying about it due to media hype? 

Alasdair-G: Thank you Martin, I was just looking to improve my diet as I have quite a sweet tooth.  By cutting the level of sugar in my diet I was thinking that would help me get in shape quicker for the season.

I have seen a lot in the media lately about the level of sugars in fruit juice and thought it was a t(r)opical question (sorry about the pun!). 

Would a glass of water or milk be a suitable alternative? Or what about effervesent vitamin tablets, do they provide a what they claim to?

Martin MacDonald: Your comment re: “cutting the level of sugar in my diet” and getting in shape is an interesting one. Reducing body fat is mostly a matter of calories and once this is in place it is about fine tuning other factors such as macronutrient intake, timings and food sources. 

If by cutting out the fruit juice you reduce calories, you may well lose body fat but if you cut out the same amount of potato for instance, you could well achieve the same results. The question then is… which is easiest and most optimal to remove. Swapping the fruit juice for water or milk are both potentially useful options, the water is a complete reduction in calories and the milk swaps some of the sugar/carbohydrate for a little fat and protein.

Vitamin tablets provide vitamins… whether these are useful is dependent on the rest of your diet as a whole. Hope that helps!

paulc1980: Hi Martin, I’m reading a book called ‘Pure, White and Deadly’ by John Yudkin.

It details how the modern diet is very high in sugar. So far he hasn’t distinguished between different types of sugars so it reads like all sugars are bad for you. This contradicts what I picked up from training over the years where we should look for complex sugars rather than simple sugars. Whats the reality? Is the high carb diet adopted by endurance athletes bad for us in the long term?

Martin MacDonald: Hi Paul, cool book. There actually aren’t technically simple and complex sugars, all sugars would be termed ‘simple’. Unfortunately, and something I have been quite vocal about before, is the use of the terms simple and complex, in relation to carbohydrates. They are now completely outdated. White bread, for instance, is a ‘complex carbohydrate’ but we know it acts very much like sugar (glucose) in the body.

The reality is, those doing a large amount of exercise can eat a lot of carbohydrate in many cases. Others simply do not seem to do as well with lots of carbohydrate even with large amounts of exercise, and this will vary dependent on the type of exercise. Sugar is something quite different to the overall content of the diet as it may promote over eating… again, not an issue if you are a lean triathlete who struggles to consume enough food anyway.

For the general public, added sugars are probably an issue, but this doesn’t mean avoiding whole foods that contain sugar as some zealots might have you believe.

My main issue, that might be coming through in a few of my answers now, is when people eat more carbohydrate but at the expense of fat and protein. I have an article on the Mac-Nutrition website titled: A low fat diet worsens cardiovascular risk factors in… runners” that might interest you.


Martin will be speaking at the Triathlon Show, taking place at Sandown Park in Surrey from 28 Feb to 2 March. More details at