Blood Sugar

#246: Ketosis VS Fat Burning (Beta Oxidation), Carb Cycling on Keto w/ Peter Defty

by Mike Mutzel




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About Peter Defty:

Peter has spend the past 17 years tinkering with his Optimized Fat Metabolism (OFM) model to help athletes to consistently obtain the “game-changing” performance and health benefits.

Peter helped recruit fat-adpated athletes for Steve Phinney and Jeff Volek's FASTER Study (Published Volek


Show Notes:

02:10 Peter’s Journey: Peter ran his first marathon, doing the traditional carb load. His performance and condition suffered. He asked “What did the Masai do?” The Masai go all day on a diet of meat, blood and milk. Peter started increasing protein and fat in his diet with a small amount of carbs.

04:16. We were underutilizing our ability to metabolize fat for performance. At the time, endurance athletes were heavy into carbs. When carbs were removed, everything started to work better.

06:53 In 2010 he connected with researcher/clinician Steve Phinney, MD PhD. Phinney had done a fat adaptation study with cyclists in the 1980s in an attempt to prove that carbs were the better fuel. He found far different results. Phinney’s research and fellow researchers were thus black listed in academia.

09:14 Peter and Phinney’s relationship brought Peter data to confirm his findings and it brought Phinney a pool of endurance athletes in one sport from which to extract data.

10:09 Western States 100 Study inspired the FASTER study of metabolic differences between high carb and low carb endurance athletes by Phinney and Volek.

12:10 Fat adaptation/metabolism is about beta oxidation. Beta oxidation occurs within the mitochondria of the cell and is difficult to measure directly. We measure ketones as a proxy.

13:53 Glucose and ketones are interchangeable fuel sources for the aerobic spectrum, though not as much in high intensity. There you are running an oxygen deficit and going into glycolytic spectrums.

14:52 When you are highly fat adapted, ketone levels are not highly elevated It is not the level of ketones in your blood that is most important. It is what you are burning.

15:47 Some athletes will run high glucose and low ketones.

16:20 Fat adapted athletes replenish glycogen despite not consuming carbohydrates. When you are fat adapted, your body will produce the energy substrates to meet your metabolic need. When pushed into the glycolytic spectrum, your liver is signaled to release glucose. There will be a mild ketone rise and a sharp blood glucose spike.

18:47 Most ketosis studies have been performed on relatively sedentary subjects. Fat adaptation with performance athletics is very different. The aerobically fit athlete is not easily kicked out of ketosis. The window of carbohydrate tolerance and flexibility opens wide.

22:59 You need both aerobic training and HIIT. When you build an aerobic base on a fat burning physiology it is powerful.

25:19 Mitochondrial density and capillary density are the foundation. First build the energy/oxygen delivery system: heart, lungs, capillaries, and microcapillaries.  You need microcapillary biogenesis to feed the muscle cells.

26:25 Fat adaptation reduces inflammation. You need to add salt and fluid to your diet, especially when you are sweating. You have that ability to grow cardiovascular piping to deliver more fluid.

27:37 Women athletes who try to do straight up keto often encounter adrenal stress. Some men also experience this, especially those who have high stress elsewhere in their lives. They lose weight when they add carbs back in and can get through their workouts comfortably.

29:22 Chronic high stress/cortisol can cause weight gain, even when an athlete is hardcore keto. Stress is as big of an issue as carbohydrates in fat adaptation.

31:14 Circadian rhythm disruptions ping our cortisol, dopamine and other chemicals that hinder fat burning.

34:41 Biological science looks at one certain aspect and attempts to control the variables. We interpret this as an absolute and applicable in the real world. The real world has multiple dynamic variables.

39:48 Peter wants people to eat the entire animal: organ meat, skin and connective tissue, as well as muscle meat. In a diet of vegetables and the whole animal, you have a balanced dense diet and you only need to eat a little in the way of animal products. You can do more with less. The less you eat, the longer you live.

41:56 When Peter’s vegetarian athletes take desiccated liver capsules and gelatin capsules, injuries stop and performance goes through the roof.

42:37 We are omnivorous carnivores. The human digestive tract is closer to that of a dog than a pig. Pigs and bears are true omnivores. Our eyes are in the front of our head and we only have one stomach.

43:30 In winter, our feeding window is smaller due to circadian rhythms. We would be more keto in the winter. Carbohydrates would not be readily available to our ancestors. Peter has his athletes on a mega dose of vitamin D in winter.

45:17 When you are well fat adapted, alcohol and fructose become useable energy substrates. Both are metabolized similarly in the liver, converting it into fat. If you are fat adapted, your body does not let the fat accumulate.

46:22 The main ingredient in Vespa is a natural biologically active peptide derived from the giant Asian wasp. The wasp must have the peptide to be able to metabolize fat at a high rate. Not a lot of research has been done, but people find it to be very effective. Vespa is used as a catalyst, not calories. Vespa is not just for performance athletes.

51:07 Recovery is faster with ketosis and Vespa because you haven’t done the damage in the first place. When you burn sugar, you create oxidative stress, which damages cell membranes and your mitochondria. When you metabolize fat, you are providing yourself with nutrition in a way that optimizes your body. When you are not doing the damage, you get stronger faster.

56:48 Peter’s Morning Routine: Peter has young children, so mornings are a free- for-all. He has a cup of coffee with heavy cream and a small amount of sugar. He won’t get hungry until 2 or 3 o’clock. He prefers to do long runs on trails in the mountains. It is great thinking time.

58:22 Peter’s Desert Island Nutrient:  Coconut. Ancient people had it figured out. Relax. Eat whole fresh foods. Eat produce in season and fresh meats.

59:29 We have a great deal of fear-based thinking about food.  Be flexible about your food. Peter finds there is no significant difference between organic and non-organic foods. Don’t get caught up in the fear and stress.

01:01:52 Peter’s Elevator Speech: We need to teach our bodies to get back to burning fat.  We have to look at the metabolism even more than food or diet.






  1. Hi Mike! Peter said he often recommends desiccated liver capsules. Do you have a trusted source? I found many online but I’m not sure how to determine the quality of a product like this. Traditional Foods makes great products like this, Chris Kresser recommends them, but they often seem to be out of stock. Wondering if you might ask Peter what his go-to is. Thanks!

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