Elite cyclists are extremely dedicated to their training plans. Surprisingly, many of these same athletes don’t give their nutrition similar attention, despite the fact that the combination of proper training and a sound sports nutrition plan is the key to success.

A good nutrition plan includes proper amounts of each macronutrient (protein, carbohydrates, and fat). Athletes need to give their bodies these nutrients to enable them to perform, repair, and recover properly. Athletes also need to pay attention to overall general health, including a strong immune system.

One area that is still largely misunderstood, though well studied, is protein for endurance athletes. Most of my clients come to me with nutrition regimes containing too much protein and fat and not enough carbohydrates (their main fuel source). There seems to be a common belief that we need more protein, but in reality excess protein doesn’t benefit the endurance athlete. Click through to read why….

Research indicates that endurance athletes should consume a diet of approximately 55-60% carbohydrates, 20-25% fats, and 15-20% protein.[i] This axiom does have some flexibility, though, and it’s important to look at grams of carbohydrates and protein per kilogram of bodyweight as well as percentages when making a detailed plan. Grams per kilogram can be altered based on intensity/duration of training. For example, an athlete could consume between 5-10 gr/kg of carbohydrates during exercise, but not everyone is the same. Some Kenyan marathon runners have reported consuming diets of up to 70% carbohydrates. Ratios of carbohydrates, fats, and proteins may also change before a big endurance event if loading up on carbohydrates.

Although research supports using carbohydrates as a main fuel source for athletes, the billion-dollar diet industry pushing lower-carbohydrate and “zone-esque”-like diets still seems to have athletes jumping onto the higher-protein, lower-carbohydrate bandwagon. Whether it’s an attempt to lose weight or simply because media has led them to believe this is what they need to do, it’s a mistake. These diets are a recipe for disaster for an endurance athlete. Although we do need protein, it is not the endurance athlete’s fuel of choice during exercise, and it can’t make up the majority of one’s fuel.

Carbohydrates and fats are the necessary fuels for energy. In the sports nutrition community, carbohydrates are often said to have a protein sparing effect. This means that we should eat approximately 5-10 gr/kg of carbohydrates, depending on our training intensity, in order to spare the protein for its routine uses in the body. Protein is required to make antibodies for the immune system. It builds tissues such as hair, nails, skin, and muscle, and amino acids make enzymes and hormones. Protein is also required to make hemoglobin, which is needed to transport oxygen to exercising muscles. If we don’t eat enough carbohydrates, we’ll have to break down protein within body tissues as a source of fuel, and this is very inefficient. When the body has to resort to protein for fuel, it will rob the body of the protein needed for its many important uses. Protein has a slow gastric emptying rate (it stays in the stomach longer) and therefore is not the food of choice while on the bike (although small quantities of protein in sports drinks is still up for debate). Protein is clearly very important to our health and recovery.

What is important to remember is that protein is not a major source of fuel during exercise (exceptions could be an Eco Challenge or an event lasting more than fifteen consecutive hours). Even if you consume more, this will not change.

Based on nitrogen balance it can be estimated that protein contributes about 5-15% to energy expenditure at rest. During exercise, in relative terms more amino acids may be oxidized. In relative terms, however, protein as a fuel is not important because of the much greater increase of carbohydrate and fat oxidation, which are your main fuel sources during exercise. Therefore during prolonged exercise the relative contribution of protein to energy expenditure is usually much lower than it is at rest, usually well below 5%! In extreme conditions when carbohydrate availability is limited, this can rise to 10%.[i]

You can see why endurance athletes will not benefit from higher than recommended protein diets.

The recommended intake of protein for the average person is 0.8 gram per kilogram of body weight. For endurance athletes the recommended intake is 1.2 to 1.8 g/kg.[i] Studies show that endurance athletes need 1.2-1.4 g/kg body weight to maintain nitrogen balance. Excess protein will not help cyclists perform optimally. In fact, excess protein is simply stored as fat.

Some researchers believe there is no need to increase protein higher than the average person (0.8g/kg). The opposing view recommends the range mentioned above (1.2-1.8 g/kg). One interesting observation scientists have made is that training seems to have a protein-sparing effect; the better trained an athlete is, the less protein oxidation occurs.[ii] This supports the idea that we don’t require excess protein in our diets and may be fine with the amount recommended to the general population (0.8 g/kg). I believe different individuals can succeed with different ratios of protein, and athletes for the most part aren’t having any trouble meeting the bare minimum. Personally, I’d aim for between 1.2-1.8 g/kg. If your immune system is consistently strong, your overall health is excellent, and you’re within the above ranges, you’re on the right track. But why leave anything to chance if your goal is to reach your best yet?

The timing of your protein intake is important. For example, post-workout protein intake combined with high glycemic carbohydrates can increase protein synthesis. Studies suggest that ingesting 15-20 grams of protein post workout in combination with the proper amount of carbohydrates for your weight (1.2 gr/kg) is enough for optimal protein synthesis.

The type of protein is also important. Whey protein, for example, is easily digested and superior to soy protein. It is also a simple option for a post-workout smoothie. Combining carbohydrates and protein not only refuels your glycogen with the carbohydrates, but also creates an optimal environment for absorption of amino acids. “Increased availability of glucose and amino acids also results in increased plasma glucose concentrations, which in turn may cause a reduction in protein breakdown and a small increase in protein synthesis.”[ii]

You may already be eating protein within the recommended range of 1.2-1.8 g/kg for endurance athletes. Even Tour de France athletes whose diets have been closely followed (some consuming 7000-9000 calories a day) are able to meet their protein needs simply by increasing their overall caloric intake, as almost all foods have some protein in them. Generally speaking, there is a linear relationship between energy intake and protein intake, and if you’re matching your energy expenditure for the day you shouldn’t have to add protein supplements to your diet. Having said this, whey protein powders are often used for convenience and for their easy digestion. I encourage my athletes to consume some type of smoothie most days of the week, as it’s an easy way to get a lot of nutrients.

The bottom line is this—protein is crucial for the active athlete, but more is not necessarily better. Get the timing right, get the grams per kilogram right, and journal your nutrition for a few days to be sure you’re consuming the proper amount for your diet. Or hire a professional sports nutritionist to do the work for you.

I know you’ll get your hours in on the bike this week, but will you refill your tank with the right fuels in the proper amounts to get the most return from those hard training hours? If you want to have the most powerful season yet, the answer to this question should be a resounding YES!


Anne Guzman is a professional road cyclist, kinesiologist, registered holistic nutritionist, and sports nutrition consultant. She provides nutritional consulting, coaching, and pre-made nutrition plans through Peaks Coaching Group. She can be contacted directly through www.PeaksCoachingGroup.com and www.nutritionsolutionsanneguzman.com.

[i] Ryan, Monique. Sports Nutrition for Endurance Athletes-Second Edition. Velo Press, March 2007.

[ii] Jeukenrup, Asker. Gleeson, Michael. Sport Nutrition-Second Edition. Champaign, IL; Versa Press, 2010.


  1. The shift in the nutrition world to low-carb is really about having one’s body be more effective to burn fat rather than carb/glucose for fuel. It’s not all about high protein intake. That’s just one step in a much bigger plan. A lot of endurance athlete’s that do low carb focus on increasing fat intake (ie Paleo). It’s against conventional wisdom so that’s why there’s lots of for/against battling going on. Lots of resources about this so a quick Google search works. Joe Friel has a book on endurance athletes and the Paleo diet.

    I’m neither for or against low-carb. It’s best to do your own research, try it out, and see how you handle it. It may or may not work but best to try it out before picking sides.

  2. Futurefunk: there are also a large number of people who think that they need more protein because they are breaking down their muscles a lot and want to build bag strong. I will not debate the validity of the Paleo diet as I am not qualified to do so, but cyclists must remember that we are not body builders and that having huge muscles is normally going to be a disadvantage, not an advantage

  3. Jordan, it’s still a fundamental issues of calories in > calories out that is responsible for weight gains. Fiddling with the balance of protein/carb/fat for a given diet isn’t going to change things too much, especially if you train the same (miles, miles, miles rather than hills, hills hills or sprints, sprints sprints)

  4. for a few years when i thought i was fast on the bike, i followed the paleo diet for athletes. Check out the highlights here: http://www.trainingbible.com/pdf/Paleo_for_Athletes_Cliff_Notes.pdf

    The main take-away is the TIMING of the protien and carb intake in relation to exercise. The percentages that are recommended by the Paleo diet and the Peaks Coaching plan are not that different. Peaks says 15-20% protien, 55-60% carb, and Paleo says 20-25% protien and 50% carbs. So, what are we talking about here–5 grams of protien more or less for an 80kg rider? The point is–low carb when you are NOT riding, and only use the carbs for the fuel your body needs when you are riding. And, this is what I take away from this article as well. I can say that when i did switch over to this type of nutrition timing my recovery was much better and power stronger than eating the same calories and percentages haphazardly.

  5. The value of carbohydrates for endurance athletes has been vastly overestimated. Slow twitch muscles run on fat. Insulin blocks lipolysis and in some will lead to lipogenisis even in caloric deficit. Ketogenic diets have been shown anecdotally to increase vo2max.

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