by Jonathan Bechtel in Health + Nutrition, image by -Snufix-

Secrets From The Savannah: What the Diets of Elite Kenyan Runners Teach Us About Optimal Nutrition

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East african runners have a record of dominance in elite distance running. Since pushing themselves into the spotlight by steamrolling the competition in the 1968 olympics, Kenyans and Ethiopians have enjoyed a peculiar success at international events. Since that time they’ve grabbed 10 of the 20 top times for middle and long distance cross-country races.  This success naturally led to curiousity about these runners’ origins and practices.

Studies of their biology, conditioning, and nutritional habits have been both illuminating and confusing. A surprising fact discovered by western researchers was that running prowess is not evenly distributed in these countries. Within Kenya and Ethiopia are different geographies, cultures, and tribes that create very different lifestyles from one region to the next. It was eventually discovered that the majority of Kenyan runners came from a small ethnic group called the Kalenjins, who live in the Great Rift Valley in northern Kenya. They make up less than 10% of the Kenyan population, but won a staggering 40% of middle and long distance races in international competition  from 1987 to 1997.Such a story naturally stokes the imagination. What is it about this band of people that makes them world-class runners? Is it in their genes? Was it a culture that glorified running? Was it something special in their diet? Ensuing research provided some answers, but no silver bullet.

You could write a book (and some have) about all the unique wrinkles in Kalinjin life that led to their running prowess, but this article will slice one important variable: their diet. Any runner knows the importance of nutrition in a training regimen, and studies of Kalinjin eating habits both re-affirmed currently held beliefs while raising doubts about others.

Ingredients

Whenever a mysterious tribe or part of the earth is discovered, rumors quickly spread about a new superfood or diet with extraordinary health properties. Acai berries, mangosteen fruit, and chia seeds are the products of such hype. Did the Kalinjin diet have a special ingredient? Would their eating habits shed new light into running and nutrition the same way the Okinawans did for longevity? The answer is a decisive no. The Kalinjin diet, it turns out, is pretty plain.

Surveys and observations done in person confirmed that a typical day’s food consists of cabbage, potatoes, kidney beans, boiled rice, and ugali, a paste made from corn maize. Drinks usually consisted of water and tea. The nutritional quality of all these foods was high, but none were out of the ordinary. Overall macronutrient intake among Kalinjins conformed to traditional canons of athletic nutrition, and studies of their diet confirmed conventional beliefs about the macronutrients you should consume in your diet and did not turn over any new leaves.

The proportions of food groups consumed by Kalinjins also came as little surprise. A careful study published in the Journal of Sports Nutrition and Exercise Metabolism found that most elite Kenyan runners received 70-80% of their calories from carbohydrates, followed by protein and fat. Other studies reported similar results. These proportions align with recommendations typically made by exercise scientists for endurance athletes.

Energy Intake

What did comes as a surprise was the amount of calories consumed. Given their activity levels, Kalinjins don’t eat very much. A famous survey published in the World Review of Nutrition and Dietetics found that Kenyan distance runners consumed an average of 2250 Kcal a day, more than 1000 less than their average daily expenditure. These figures were shocking when first published. How could the world’s most elite runners consume fewer calories than the average american?

It turns out the figure was slightly biased. The survey relied on self-reporting, and the Kenyans were not always accurate in estimating their caloric content. Further studies adjusted the figure upward, but did not overturn the fact that most Kenyans are in negative energy balance in periods of intense training. Almost all Kenyans experience a significant reduction in their BMI in periods leading up to a race.

The same was true of their fluid intake. Most runners don’t drink anything before their 10-15 mile runs in the morning, and the majority of kenyans don’t re-hydrate during races. At first glance, these practices seem sub-optimal. After all, the importance of carb-loading and being well hydrated have been staples of western training regimens for years. So who was right?

A re-consideration of the literature on the biomechanics of running suggested these seemingly counter-productive habits actually conferred a benefit to Kenyan runners. Because their diet is high in carbohydrates, the majority of Kenyans metabolized extra fat during periods of negative energy balance, which reduces their BMI without significantly affecting their glycogen stores or oxidative capacity. This effect was enhanced by the fact that Kenyans typically eat right after a meal, negating the glycogen depleting effect of negative energy balance. At race time the reduced body mass lowers the energy cost of locomotion without affecting maximal energy producing capacity.

Repeated studies revealed negative energy balance and BMI reduction before races to be a regular occurrence for Kenyan runners. For example, world-record marathoner Margaret Okayo weighed only 39 kg when she won the 2004 London marathon, 4 kg below her usual weight. Kenyan Felix Limo weighed 59 kg when he won the 2005 Chicago marathon, but weighed 64 kg a few weeks before the race.

While severe BMI reduction before a race can give a runner a competitive advantage, it is not without long-term costs. Muscle fatigue, prolonged workout recovery, and an accelerated deterioration of athletic performance are all associated with low caloric intake, and these effects are seen in Kenyan runners. While Kalinjin runners shine brighter than any others at their peak, they also burnout faster. Kenyans do not enjoy the same longevity as distance runners from the west, presumably for this reason.

Conclusion

Of course, the importance of diet for the Kalinjins needs to be seen as part of a greater context. Other studies have suggested that Kalinjins might enjoy a genetic pre-disposition to body types well suited for distance running, and cultural factors undoubtedly play a large role in their success. Running is a social activity in Kalinjin villages, and a male Kalinjin adolescent is often running 80-90 kilometers a week by the time he is 18. Their sustained success has also given Kenyans a psychological benefit. Surveys of distance runners suggest that both western and east african runners believe Kenyans are inherently superior at running long distances, and that this confidence encourages more Kenyans to pursue the sport with vigor and supplies a modest placebo affect.Ultimately, a close look at the Kalinjin diet reaffirms a lot of things committed distance runners already know. A high carbohydrate diet with a solid nutritional content has long been considered the dietary regimen of choice for endurance athletes, and the success of Kenyan runners only cements that fact. The concept of negative energy balance should be noted, but also viewed alongside longer term aspirations. Becoming a better runner is something we all strive for, but for many of us running is a way of life that we ought to hold on to for as long as possible.




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