In the second of two articles for womencycling.ie Beth McCluskey gives us an in-depth analysis of what she thinks of high fat low carbohydrate and paleo diets, two diets which are very popular with athletes at the moment.
What do you think of high fat low carb diets?
High fat low carb diets are nothing new and have been around for over 100 years. In recent times they’ve become very popular, especially with athletes. The most well-known version of the LCHF is probably the Atkins diet and more recently Gary Taubes, Jeff Volek, Steve Phinney and Tim Noakes have proposed the LCHF diet as the answer to western society’s issues of obesity, type II diabetes crisis and cardiovascular disease, as well as the answer to enhanced physical performance for athletes.
LCHF diets can indeed offer a short term solution to an individual with obesity and diabetes, but it is not the only solution, and it is not a long term solution by any means. It is important to distinguish between the metabolic biochemistry of an athlete and an obese person. There is an inherent danger in being so focussed on macronutrients and ratios that we lose sight of food and the complex nutrient interactions that occur within food and within the body.
The LCHF lobby will argue that carbohydrates are the main cause of obesity, diabetes and cardiovascular disease, coupled with the fact that the low fat recommendations of the last century appear to have contributed to the health crisis we now face in the 21st century. Some extremist LCHF lobbyists will claim that nutrition scientists who don’t endorse this view won’t have read or understood the right research and their views are out of date or biased. The reality is that nutrition science is far more complicated than that.
In the low fat era of the past correlation between fat intake & cardiovascular disease resulted in nutritional guidelines recommending a reduction in fat intake and an increase in carbohydrate intake. While the experts meant us to eat less red meat and eat more vegetables and wholegrains, the food industry had other ideas and responded by producing a vast array of tasty & cheap low fat versions of foods that were high in sugar, salt and processed oils. The focus on fat as being bad and carbohydrate being good was interpreted as a licence to eat anything as long as the macronutrient content was correct. The long term damage this has done to human health is now becoming apparent and we urgently need a solution.
LCHF proponents will argue that since low fat high carbohydrate diets have caused the crisis then the opposite will cure it. However, when macronutrients are taken out of context from food we invent mutually exclusive diet choices that are restrictive, nutritionally inadequate and unhealthy. By only focussing on the low carbohydrate or high fat content of a diet we are demonising all low carb foods and endorsing all high fat foods as if these are the only considerations.
A high fat meal of highly processed ingredients, that is high in salt and high in preservatives (such as sausages and bacon) is completely different to a high fat nutrient-rich meal (such as mackerel, nuts and avocados). Equally, a low fat high carb meal of highly processed sugary cereals is different from a low fat high carb meal (for example sweet potato & vegetables with quinoa). There are people all over the world who live long & healthy lives on both high fat and high carbohydrate diets.
Health problems only occur in these populations when they adapt a ‘western’ style diet. Focussing on just fat or carbohydrate rather than food just gives us another excuse to eat badly. It is this very concept that led to the crisis we now face, but replacing one fallacy with another is not the answer. We need to focus of real food and not macronutrients if we are to find a long term solution to the health crisis.
What do you think of LCHF diets with regard to athletic performance?
With regard to athletic performance, for me there are 2 considerations when implementing a nutrition strategy for an athlete:
1. The current and future health of the athlete
2. If the strategy is going to improve their overall performance
Regarding the LCHF approach we do not know the long term effects of a high fat diet on healthy individuals. There is limited research on the topic and in my experience it doesn’t actually improve performance, except perhaps in extreme ultra runners and adventure racers.
Cycling is a unique sport requiring endurance, speed, power and strength. Lots of different types of athletes have adopted the LCHF strategy as a lifestyle choice and there seems to be a certain obsession with blood glucose, insulin and lipoprotein profiles, as if these were somehow the only indicators of optimum health and performance. These are useful indicators but they don’t tell us the effects of lipids on other aspects of the body. Lipids are made up of fatty acids and glycerol. Individual fatty acids play a potent biological role in the functioning of all cells and until we can determine the exact impact of a high fat diet on the immune system, liver and kidney function, the gut microbiota, bone health, the brain, the blood, the vascular system it would be premature to recommend this as a safe long term strategy for athletes.
However, in the short term, manipulation of carbohydrate, protein and fat intake can induce favourable training adaptations, training with low muscle glycogen and training fasted at certain times of the training phase can help improve endurance adaptations, and likewise other training adaptations for speed, strength and power can be improved by training with adequate or high carbohydrate stores. Optimising the timing and quality of protein intake can enhance strength adaptations. Athletes who require more than pure endurance need to be metabolically flexible to get the most out of their training. This needs to be done while meeting all the other nutritional needs of the athlete health and well-being.
There is no one size fits all, every individual is unique and some people respond differently to others so adapting a LCHF diet as a lifestyle choice may not be the route to making you a faster, stronger, fitter cyclist or a healthier individual. The question we really need to address is not whether we endorse low carb or high carb regimes but how can to get the best out of the individual athlete. I would urge athletes to stop focussing on carbohydrate and fat and eat a balanced diet that is based on natural whole food.
Talk to us about the Paleo diet.
The Paleo diet has been around a long time too. I remember when I was racing seriously over ten years ago it was all the rage on the elite MTB scene in Europe for a season. It has been popularised by Loren Cordain, Gary Taubes and Rob Wolfe and is now part of the mainstream diet scene. They argue that we our genes have not changed in 10,000 years and we should be eating like our ancestors of that time.
Part of this argument is true, our genes have not changed that much in the past 10,000 years but the expression of them has. Epigenetics is the study of how genes are expressed in response to the environment to which they are exposed. This extends to animals and plants as well as humans, the environment we live in is very much different to our ancestors and our genome and the genome of animals and plants will constantly change and adapt. We don’t actually know exactly what our ancestors ate or the state of their health, we can be pretty sure it wasn’t French beans, broccoli or carrots as we know them.
Despite the bad science, the concept of eating lots of whole foods is a good one. However, the elimination of all grains and dairy products is a fundamentally flawed approach to human nutrition. I am 100 per cent for reducing our intake of processed grains but whole grains provide lots of minerals and vitamins, soluble and insoluble fibre, phytochemicals and antioxidants that are important to human health and to athletes. Eliminating white bread, pasta and rice makes sense; eliminating quinoa, buckwheat, barley, unprocessed rice does not. Likewise, eliminating dairy foods for athletes is not advised. From a performance point of view the milk proteins are rich in the amino acids that promote recovery and optimal adaptation to training.
The fact that the Paleo diet bans dairy and grain, but allows whey protein and dextrose for athletes makes very little sense to me. More worryingly, cyclists (male and female) are more at risk of developing osteoporosis and osteopenia than non-cyclists. Dairy products are a rich source of calcium but also contain magnesium, zinc, selenium, conjugated linoleic acids, LA & bioactive peptides that all exert favourable actions on bone mass. Calcium absorption from milk is optimised due to the presence of lactose, protein & the ratio within calcium & phosphorous. There is no sense in excluding a moderate consumption of dairy products from the diet unless an intolerance or allergy is present. 70% of the world population lacks the enzyme B-galactosidase which breaks down the milk sugar lactose but most Europeans do not and can tolerate lactose in milk (another example of epigenetics). We will possibly see more cases of low bone density and osteoporosis in younger adults & athletes in the future as extreme diets such as LCHF and Paleo become more popular. I have heard of 2 recent cases in the male peloton where young men in their thirties have been diagnosed with severe osteopenia. This is extremely worrying.
No diet or lifestyle choice is worth risking your future health, nutrition has to fulfil all the physiological functioning of the body and protect current and future health. The definition of a fad diet is a diet that doesn’t fulfil all of these needs, so LCHF & Paleo are technically fads.
In conclusion, what is your advice to athletes out there?
My advice is pretty boring and won’t please the extremists, but here it is: eat real foods, eat a wide variety of fruit & veg, fish, meat, eggs, dairy products, wholegrain, nuts, seeds, prepare all your food from scratch and avoid all processed foods. Do not eliminate foods unless you have a medically diagnosed intolerance or allergy, choose wisely what you eat today, it will help you train well, recover well adapt well and will also determine your OVERALL health in the future.
Beth McCluskey is a nutritionist with Peak Endurance Coaching. Peak Endurance provide comprehensive training & nutrition plans and specialise in seminars and talks to clubs & groups of athletes.