Running on Fat …

Back in my marathon days (30+ years ago) I remember reading a prediction that it wouldn’t be long before women were beating the men over the magic distance of 26.2 miles. The logic was very simple, fat is an excellent fuel, fit women athletes carry more fat than fit men athletes therefore women would be better over long distances than men once they matched the men in training.

So far it hasn’t happened, fastest man – Eliud Kipchoge of Kenya 2:01:39 fastest woman Brigid Kosgei also from Kenya 2:14:04. Getting on for 10% slower.

At about 9 calories per gram fat is an excellent fuel trouble is for endurance sports the body is very happy burning glucose and glycogen even though they pack only 4 calories per gram. Stores of glycogen exist in muscle and in the liver amounting to about 600 grams. In ball park figures that’s about 2400 calories for a marathon requiring about 2600. A runner can expect to absorb 50 to 60 grams of glucose from the gut per hour which easily makes up the shortfall.

So fat burning doesn’t really get into the equation during an elite marathon. If it did even the thinnest male athlete has enough fat to go the distance.

Glycogen is king. Glycogen replenishment happens faster after a carbohydrate rich meal. What are the implications for the athlete following a keto diet? Depends who you ask. According to Harvey, Holcomb & Kolwicz the keto athlete is operating at a distinct disadvantage although it is an excellent diet for weight loss.

Dr Caryn Zinn on the other hand is more optimistic …

while Professor Asker Jeukendrup sums up what is known but leaves the question open. That article is well worth reading.

Fat oxidation rates are on average 0.5 grams per min at the optimal exercise intensity. So in order to oxidise 1kg of fat mass, more than 33 hours of exercise is required! Walking or running exercise around 50-65% of VO2max seems to be an optimal intensity to oxidise fat. The duration of exercise, however, plays a crucial role, with an increasing importance of fat oxidation with longer exercise.

There is no doubt that the reforming couch potato can successfully lose weight and burn fat at moderate rates of exercise on a keto diet. Fat around the middle is as much a handicap as lead in the saddle bags. VO2max is the upper limit of your ability to burn fuel a good measure of your fitness. More precisely it’s milliliters of oxygen consumed in one minute, per kilogram of body weight (mL/kg/min) at sustained maximum effort. In other words get the kilograms down and the VO2max goes up without any extra training.

Low Carb High Fat …

Get ready to read a lot of packets and do a lot of home cooking.

What’s in?

Meat, seafood, eggs, full-fat dairy, above ground vegetables, nuts, avocados and in moderation dark chocolate, berries and dry wine.

What’s out?

The bottom layer of the food pyramid!

Starches (including bread), sweets, processed meats, low fat or sweetened dairy, high sugar fruits.

Orthodoxy would have it otherwise …

The acceptable macronutrient distribution ranges (AMDR) are 45–65% of your daily calories from carbs, 20–35% from fats and 10–35% from protein. (healthline.com).

Ancel Keys is a goliath of the orthodoxy. His rather sketchy epidemiologic research into diet and heart disease pointed the finger at saturated fat as the cause. In 1977 a US Senate Committee issued the Dietary Goals for the United States which became the Dietary Guidelines for Americans. The American Heart Association was on board but Philip Handler, President of the National Academy of Science had this to say,

What right has the federal government to propose that the American people conduct a vast nutritional experiment, with themselves as subjects, on the face of so little evidence?

Heart disease hasn’t gone away, obesity and type 2 diabetes have soared.

There is a great deal of inertia in that orthodoxy but it is slowly crumbling under the onslaught of evidence. Ain’t nothin’ wrong with getting your calories from fat. It satisfies hunger without sending insulin levels through the roof. For some of us it may be the best option, at least for a while.

The way to plan your meals is simple. First pick your protein source aiming for roughly 1.5 grams per kilogram of your reference weight (life tables previous post). Next add a couple of serves of above ground veggies. Finally some fat stuff like avacado or nuts.

So that could be a chunk of meat with the fat on and two veg. Sounds just like the meals my mother used to cook and there weren’t many fat kids around back then.

There are any number of resources online and a shelf-full of cook books at the shop. Look for keto or LCHF, checkout Low Carb Australia on Youtube.

It is powerful stuff and it will change your biochemistry. If you are on anti-hypertensives, anti-diabetic agents including insulin, pregnant or breast feeding medical supervision is needed.