Fats or Carbs: Which Is Better Fuel?
The body’s ability to switch between burning fat or carbohydrates for fuel is known as metabolic flexibility. Unfortunately, many of us eating the Standard American Diet, or SAD for short, are not prepared to alternate between these fuel sources. Ingesting too many processed foods and carbohydrates causes our bodies to stockpile energy as fat for a rainy day…one that our diet ensures will not come.
The Benefits of Fasting Can be Lost if You’re Not Primed
A study published in the American Journal of Physiology had a group of lean people and a group of obese people fast overnight. In the morning, the two groups were tested to see what their bodies were using for energy – fat or glucose from carbohydrates.
They found that the group of lean people were using significantly more energy from fat as opposed to the obese group, which is odd because isn’t that the whole point of storing fat in the first place?
The Standard American Diet, S.A.D, Keeps Us on the Carbohydrate Cycle
When the body isn’t metabolically flexible, it relies on one of these sources primarily for fuel. Most of us consuming the SAD diet are hooked on the carbohydrate cycle, and this sugar dependency promotes not only the storing of body fat but prevents its use for energy when we fast or alter our diet.
Fitness author and former athlete Mark Sisson says the best way to get our body back to using body fat is to eliminate carbohydrates for a time, basically recommending the keto diet: high fat intake, moderate protein, and little to no carbohydrates.
A different study comparing lean and obese individuals on a high fat diet found that one single meal changed the body composition of lean individuals to burn more fat. After five days of high fat meals the obese group still showed no change in fat-utilization ability. So, while one doesn’t have to go keto forever, it is important to go longer than five days to help the body relearn to use fat for energy.
In Mark Sisson’s book The Keto Reset Diet, the goal to get your body fat-adapted is 21 days. After that, Sisson and other fitness personalities recommend introducing moderate carbs into the diet as you are now metabolically flexible.
Now, if you try a water-only fast, your body knows exactly what to do. Now, when you have carbohydrates in your meals, your body can use the glucose efficiently without sending it directly to your thighs and midline to be stored as fat. Now you’re in the “lean group”, where the body works with you to burn excess fat rather than fight against you…seemingly no matter what you do.
We Want the Body to Use Glucose and Fat for Fuel
Fitness personality Thomas Delauer says we want the body to be efficient at using glucose AND fats for fuel. Glucose is preferred when training hard; lifting weights, sprinting, or performing high-intensity workouts. We want the body to use fats for endurance work and certainly when fasting.
We are not permanently ditching one for the other, but it is recommended to consume a keto-like diet for a time in order to regain the flexibility to use both. Carbohydrates are mighty tasty, but apparently they don’t like to share power in your body.
Implementing a keto diet for a time reintroduces your body to burning all that stored fat, and then carbs and fats will work together in a bi-partisan effort to keep you lean and healthy!
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