Optimising nutrition for cycling is something that has been chewed over for many years. Attitudes have changed and, in all honesty, nothing has been made a great deal clearer despite the immense amount of money spent on research (largely funded by industry) and development of specialist products. However, while things may not be clearer to “the man on the street” the changes in intake on and off the bike over the last few decades have been dramatic in competitive cycling. This has lead to very different athlete morphologies and improved performance which has filtered through to domestic competitive cycling and recreational riders looking for an edge over their rivals. I’ve limited this blog to off the bike intake – it was getting long.


One of the interesting aspects of the interweb is the ability for people to sit at a computer and create information which can then be quoted and repeated until it becomes accepted as fact. This is not a new phenomenon – it has been done using paper for hundreds of years. The problem is the scientific basis upon which the information is created appears to have diminished and the speed with which things become accepted as facts is now out of control. As a scientist writing a blog it is hard to know where to pitch between opinion and robust evidence-based medicine. This is an opinion piece based on my experience and reading since I did my first university nutrition and dietetics course 22 (blimey) years ago. Some of it is based on solid evidence but some is openly personal experience. It is broken up into a two sections with just a couple of take away points at the end of each. Further detailed blogs to follow.

The following crib sheet may help translate some of it.

What Scientists mean:


Nutrition for health

There can be no doubt that the general Western diet has become a caricature of what it once was: high fat, high carb, low nutrient value. The amount of refined carbohydrate eaten has escalated dramatically over the last century to the point where it makes up the majority of daily Calories eaten by most. If you are still reading this post then you probably know there are two tribes advocating two main approaches to nutrition in performance exercise and you think I’ve just flashed my hand. A bit, but not quite. This is the health section.

If we go back twenty years or so, a few “facts” were established by some influential groups that shaped policy on diet. An interesting train of thought that led to “fact” and some widely held views: high cholesterol is associated with cardiovascular disease, eggs have lots of cholesterol ergo “only eat one egg a week”. Totally reasonable until you explore whether eating eggs raises your cholesterol or not and find that they don’t.

When you eat carbohydrate you break it down into simple sugars and your pancreas releases insulin so your body can use them to store as energy in your liver, muscles and fat. When you continually eat carbohydrate you continually release insulin, you lay down fat, your cells lose their insulin sensitivity and you develop diabetes and cardiovascular disease. Rather than black and white, diabetes or not, I’d like to introduce you to the idea of a grey scale of insulin sensitivity. As a population our diet in recent decades has moved us along the grey scale towards the diabetic range and prevalence of obesity and of cardiovascular disease has gone up.

When I start coaching someone, and these are always people who think they have a pretty good diet, I continue to be amazed by the amount of carbohydrate they eat. Breakfast: cereal, toast and a glass of sugar (they call this orange juice); lunch: sandwich, crisps, lump of sugar (they call this an apple); Dinner: pasta and “sometimes a desert”.

So, while there are a great many things I could talk about under a “Nutrition for health” heading, I’m going to limit the message to: refined carbohydrate is the bad guy and you’re almost certainly eating more than you need. My advice would be try two changes:

  • Carbfest to breakfast: have three scrambled eggs (no toast, no orange juice)
  • Sandwich to salad: have chicken/tuna/ham/tofu salad for lunch (homemade, easy on the dressing)

Nutrition for Cycling

You’ve got to eat fat to burn fat – David Baker 1997

June 3Rd 1966, Giro D Italia, Vittorio Adorni, Jacques Anquetil And Felice Gimondi Eating Spaghetti

As I said in the intro: dramatic changes.

Professional cyclists now pay meticulous attention to what they eat on and off the bike to the extent of obsession in some cases. Last October I saw a competition with a prize of a three course dinner with Geraint Thomas. While the chat would assuredly have been good it would have certainly been a “chips on the way home” job.

My approach to what I’d call “performance related nutrition” has changed over the last ten years or so. I grew up with the dogma depicted in the picture above that the nutritional foundation for endurance performance was carbohydrate intake. (A bit of protein to stop muscle catabolism but there would be plenty of this in the pasta.) The idea behind this was that “It has long been known” when you are exercising over about 60% of VO2max your energy source is about 70% carbohydrate and you need to replenish your muscle glycogen stores before you can train effectively again. The aim was to push up the %VO2max at which you started using your carbohydrate stores with long “fat burning” rides at lower intensity and what is called the “crossover effect up” as high as you could. Repeat and quote until “fact”.

There are two major considerations that have led me away from advising a high carbohydrate intake in performance related nutrition: bodyweight & ketones.

Bodyweight has great importance in cycling. Alex does the physics stuff but, if I may, when riding a bike you produce power against resistance comprised of the air you need to push out of the way to move forward, the mechanical inefficiencies of your machine and its interaction with the road and gravity. Most recreational cyclists hate climbing to the extent that they invest in lighter components to shave 10s of grams from their bikes while paying little attention to losing a bit of weight off themselves. In a Grand Tour stage with a mountain top finish “marginal gains” have been made by getting leaders to the finale in a state of “conditional dehydration”. That is to say, dehydrated to the point where they are willing to sacrifice W for Kg to gain a performance advantage.

Not even a square of chocolate? Vidya Navaratnam 2015

So why does not eating carbs make you lighter? There are short term and long term considerations. Carbohydrate stored in the form of muscle and liver glycogen weighs a lot because of all the water stored with it. If you cut out carbs for four days or so you’ll lose in the region of half a stone. Go on, try it! This was shown in a simple paper in the American Journal of Clinical Nutrition 25 years ago. However, you’ll feel like rubbish if you try to do anything much above 60%VO2max on your bike: see above (it wasn’t all wrong). So what you need to do is press on and feel rubbish for a bit and introduce some carbs while you’re riding.

When you’ve stopped eating carbs for a few days, as well as feeling rather odd and flaky at times, your liver starts making ketones from fat. I get a very dry mouth with a slight metallic taste but thankfully not the bad breath that others report which appears to be different from the classic pear drops smell of DKA. (If you want to flush out the crazies with their “facts” put ketogenic diet into Google and while away the hours. In fact, I wonder if writing a blog will really draw them out?) Ketones have always been associated with illness namely type one diabetes and starvation so to use them in a performance related nutrition might at first seem a little bit odd.

A friend who is an international athlete recently asked me for some advice on nutrition for some particularly long arduous events and I suggested he look into this topic of very low and low carb diets. His initial response included a comment along the lines of “why isn’t Froome doing it”. Well, “It is believed that” he uses techniques based on these ideas. Ketones are a great fuel source for muscles but weren’t on the radar of physiologists when the fundamentals of carb/fat crossover were becoming “fact” and research is only just catching up with this third contributor. I think Chris Froome probably uses a low carb diet to keep very lean, takes in carb on the bike in the form of cluster or cyclic dextrin with a few other bits and bobs (another blog) and then, when it’s hammer time, the car passes up the bottle with the synthetic ketones and the stem-gazing begins. It’s just that last bit that us mortals without finances to run to £1000 a bottle energy drink can’t do.

I’ve found the longer term gains of a very low carb diet are feeling much less susceptible to sugar lows, “bonking” on rides and endurance seems to improve. Once you have gone through the first couple of weeks of being on a very low carb diet you begin to feel a threshold of intensity where you are comfortable that you can keep going at for much longer than you would previously have thought. After a period of adaptation, putting carb back into on the bike intake lets you rapidly get back to some higher intensity training and, I have found, maintains the benefits.

When doing this type of carb restriction I would recommend splitting meals to five times a day, making sure you get >20g protein every 2.5-3.5 hours, keeping well hydrated and taking supplementary dietary fibre!

As a doctor I don’t think I can quite advise a very low carb diet for long durations. However, I think as a tool to understanding your body, losing some weight and maybe gaining some performance I think cycling it with a low carb diet is a good idea. I was always fairly ectomorphic and thin but these ideas allowed me to get very lean and move my FTP to over 5W/Kg after putting on quite a bit of weight over the years. (I’ll spare you the pictures.) The other continued benefit is the endurance out over five hours for long events.

Unless you are planning coming out of the traps all guns blazing in the spring, now would be a great time to try a very low carb diet for a couple of weeks and see how you react. The weather is rubbish so what have you got to lose apart from a few pounds!

My advice:

  • Try a very low carb diet for a couple of weeks and if you manage it add in carb on the bike and then small amounts post training
  • Take high dose fish oils morning and evening












7 thoughts on “Nutrition off the Bike: Feast or Famine? Carb or Cow?

  1. Inspired me enough to put The Boss to one side and to start re-reading Briffa’s ‘Escape The Diet Trap’.

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