The human body has evolved to be less fussy about what foods it can utilise for energy.
All macronutrients (carbohydrates, fat and protein) get used as fuel in some way depending
on a variety of circumstances including which individual macronutrient is in abundant supply.
For example, when carbohydrate (glucose) is low, the body burns an increased proportion of fat.
All macronutrients (carbohydrates, fat and protein) get used as fuel in some way depending on a variety of circumstances including which individual macronutrient is in abundant supply. For example, when carbohydrate (glucose) is low, the body burns an increased proportion of fat.
Exercise scientists have tried for many years to develop diets that make use of the vast fat stores of energy we all have (it’s much more than glucose), yet still maintain the use of glucose for the more intense aspects of sports competition and high level performance. Marathon running is a good example. Fat will fuel the endurance part of the race, especially in the later stages, but when it comes to a sprint up a hill or to the finish line, the research says that unless those enzymes that get glucose from storage are operating at peak efficiency, you will be slower in the sprint. Another example is that you will not be able to lift as much at the gym if you eat a low carbohydrate diet. Eating to emphasize fat burning does just this: it degrades the response of these glucose-providing enzymes, and that makes you slower at shorter, high-intensity effort. And this process doesn’t get reversed quickly with more carbohydrate consumption. It takes time to favour glucose burning again.
Next time you feel a bit tired or lethargic at the gym or otherwise, consider the balance of your nutrition plan. It comes down to a healthy balance between all macronutrients and quality food.
