Burning Ketones In Your Body While Fasting?

ShifuYaku

I need a nutritionist, or a personal trainer to confirm, or anyone who has experience in this subject. Does it work? Have you heard about it? I read an article in Men's Journal about this topic... and I was thinking of trying it for a week. Apparently, while you are fasting, if you work out during the period that you haven't eaten, your body starts using ketones instead of sugar and it burns fat faster and more efficiently....? Is this plausible? Has anyone tried it?

McLifterPants

http://en.wikipedia.org/wiki/Ketone

Ketones are a catch phrase right now, but as you can see it can mean any number of things. In fact, many sugars ARE ketones, so using ketones "instead of" sugar makes no sense. But I digress. In terms of trying to lose weight, ignore the fads. Watch what you eat and move around more. End of story.

ShifuYaku

Is it still a good idea to fast?

Katze_e

It's working for me. I've been watching my carb intake, and it's (almost) always under 20g carb per day. I have no cravings whatsoever, I've been eating healthy, and I've lost more than 2£ in a week and a half. BUT - a keto diet is not about starving, is about making changes in your food choices, choosing protein and fat over carbs.
Also, I've done tones of diets and workouts, and nothing worked much for me before. This one, though, has been a surprise, and I'm considering to be keto for life!

MoreBean13

From Excerpt copied from:Exercise Physiology FOR HEALTH, FITNESS, AND PERFORMANCE, Third Edition, Plowman & Smith :

Ketone Bodies and Ketosis
As mentioned earlier, in order for the acetyl CoA produced by beta-oxidation to enter the Krebs cycle, a suffi cient amount of oxaloacetate is necessary. When carbohydrate supplies are suffi cient, this is no problem, and fat is said to burn in the fl ame of carbohydrate. However, when carbohydrates are inadequate (perhaps as a result of fasting, prolonged exercise, or diabetes mellitus), oxaloacetate is converted to glucose. The production of glucose from noncarbohydrate sources under these conditions is necessary because some tissue, such as the brain and nervous system, rely predominantly on glucose for fuel (Marieb, 2007).
When oxaloacetate is converted to glucose and is therefore not available to combine with acetyl CoA to form citrate, the liver converts the acetyl CoA derived from the fatty acids into metabolites called ketones or ketone bodies. Despite the similarity in the names, do not confuse ketones with keto acids (pyruvic acid and the Krebs cycle intermediates) (Figure 2.9). There are three forms of ketones: acetoacetic acid, beta-hydroxybutyric acid, and acetone. All are strong acids. Acetone gives the breath a very characteristic fruity smell.
Ketone bodies themselves can be used as fuel by muscles, nerves, and the brain. If the ketones are not used but instead, accumulate, a condition called ketosis occurs. The high acidity of ketosis can disrupt normal physiological functioning, especially acid-base balance. Ketosis is more likely to result from an inadequate diet (as in anorexia nervosa) or diabetes than from prolonged exercise, since the muscles will use the ketones as fuel. During exercise, aerobically trained individuals can utilize ketones more effectively than untrained individuals.

TerraLea

I was told that if you workout after eating preferably a liquid breakfast (example, protein shake) your body will burn fat. If you workout on an empty stomach your body will burn some fat but also muscle (you don't want to do). Fasting may be okay, but you may lose more muscle than fat when you workout.

I don't know how true this is, just wanted to share with you.

cordianet

In general, where you and I are at in our weight loss journeys, I'd say no, fasting is probably not a good idea. You can certainly try it if you want, but fasting, especially IF (Intermittent Fasting), which is what I think you are referring to, is really designed for people trying to go from lean to VERY lean. Like on the order of 10% BF to 7%. It's benefit for overweight and obese folks is less clear and may actually cause some problems. Now, that said, there are some people that do promote fasted exercise, because in theory it may burn more fat. Honestly I think the difference is pretty small and it could also cause you to perform poorly, thus negating any potential gains it might have given you. Also what they generally mean when they talk about fasted exercise is exercise first thing in the morning before breakfast, not necessarily long fasts.

In short, I'll agree with HannahOM. Eat less than you burn, make sure you do both cardio AND strength training, and make sure you're getting sufficient protein. Pretty much everything else is up for debate.

jheye

I think you are referring to intermittent fasting. Whenever you go for an extended time without eating (like overnight) you will be using fat more than glucose until you eat. If you exercise in moderation during that period, you may burn a little more fat. High intensity exercise is going to use glycogen, or muscle protein if glycogen is depleted. On the whole, I don't think it's going to be that helpful.

caraiselite

check out low carb/atkins/ketogenic diet.
that's the same thing, minus the fasting.

ketosis is pretty great, i love the way i feel once i'm in it.
the carb detox can be hard for some.

Sidesteal

Unless anyone can make a case for this being superior to any other method of caloric deficit, it doesn't really make a difference. The amount of fat you burn during a workout is irrelevant.

Fat oxidation - Fat storage is what matters and looking at the immediate effects of fat oxidation during training doesn't tell you all the information you need to in order to assess what happens to net change in fat stores.

If you're already quite lean and have issues with fatty acid mobilization then fasted training MAY help you but for the majority of people it's not going to matter.

Some reading on related topics, although the OP is covering multiple things:
http://www.bodyrecomposition.com/fat-loss/fasted-cardio-and-fat-loss-qa.html
www.leangains.com

yarwell

Apparently, while you are fasting, if you work out during the period that you haven't eaten, your body starts using ketones instead of sugar and it burns fat faster and more efficiently....? Is this plausible?

Entirely plausible, that's how the body works to keep the brain going on ketones when there isn't enough glucose around. The brain can't run on fatty acids (unlike muscles) so they are broken down to ketones for brain fuel.

The fat is being used to make the ketones, and to fuel the muscles, so in this situation more of it is being used, yes.

TheVimFuego

Nutritional ketosis is a perfectly natural and safe state to be in but if you want to be a really efficient ketone/fatty acid burner (as opposed to glucose) then you'll need time to adapt, up to 3 weeks.

It's not something you just suddenly optimally drop into because you avoided carbs for a day or so.

Some people think it is a dangerous state and may have it confused with ketoacidosis, which is harmful. The levels of ketones in the blood in ketoacidosis are WAY more than could be achieved through restriction of carbohydrate.

I burn 'em all day, every day and have been for months, lovely little things they are.

rlmadrid

From Excerpt copied from:Exercise Physiology FOR HEALTH, FITNESS, AND PERFORMANCE, Third Edition, Plowman & Smith :

Ketone Bodies and Ketosis
As mentioned earlier, in order for the acetyl CoA produced by beta-oxidation to enter the Krebs cycle, a suffi cient amount of oxaloacetate is necessary. When carbohydrate supplies are suffi cient, this is no problem, and fat is said to burn in the fl ame of carbohydrate. However, when carbohydrates are inadequate (perhaps as a result of fasting, prolonged exercise, or diabetes mellitus), oxaloacetate is converted to glucose. The production of glucose from noncarbohydrate sources under these conditions is necessary because some tissue, such as the brain and nervous system, rely predominantly on glucose for fuel (Marieb, 2007).
When oxaloacetate is converted to glucose and is therefore not available to combine with acetyl CoA to form citrate, the liver converts the acetyl CoA derived from the fatty acids into metabolites called ketones or ketone bodies. Despite the similarity in the names, do not confuse ketones with keto acids (pyruvic acid and the Krebs cycle intermediates) (Figure 2.9). There are three forms of ketones: acetoacetic acid, beta-hydroxybutyric acid, and acetone. All are strong acids. Acetone gives the breath a very characteristic fruity smell.
Ketone bodies themselves can be used as fuel by muscles, nerves, and the brain. If the ketones are not used but instead, accumulate, a condition called ketosis occurs. The high acidity of ketosis can disrupt normal physiological functioning, especially acid-base balance. Ketosis is more likely to result from an inadequate diet (as in anorexia nervosa) or diabetes than from prolonged exercise, since the muscles will use the ketones as fuel. During exercise, aerobically trained individuals can utilize ketones more effectively than untrained individuals.

I love it when you pop into a thread with some exercise science! Thanks for the read.

ShifuYaku

I was told that if you workout after eating preferably a liquid breakfast (example, protein shake) your body will burn fat. If you workout on an empty stomach your body will burn some fat but also muscle (you don't want to do). Fasting may be okay, but you may lose more muscle than fat when you workout.

I don't know how true this is, just wanted to share with you.

The article said that burning the ketones does not affect your muscle mass, as in reducing... I never heard of your body trying to eat muscle until you were completely malnourished and in famine.