When do you burn fat?

[Viper3]

The best way to understand dieting in my opinion is to know how and why your body burns fat for energy instead of carbohydrates (or muscle for that matter). If carbohydrates are the main source of energy, why is fat ever burned? If it is because there is no carbohydrates, then why is muscle used for energy when there is plenty of fat in storage? In other words, at what point in your body do you burn fat instead of carbs or muscle?

[shadowmoses]

I'm pretty sure fat is mainly burnt while you sleep in order to fuel repairing processes like cell regeneration,

ShadoW

[Viper3]

I thought carbohydrates were used for energy to rebuild cells. That is why sleeping is an anabolic phase. Which is also why you are very low in carbs after you wake up.

[gaurivaud]

great question ! IMO the first rule is that you should be in calories restictions for burning fat, but...your body should be able to burn fat, so enzyme doinf this function should be up regulated, for this purpose a high fat , low carb diet, is IMO the best way to do this. Choose the good fat, lot of mono, poly will help you

[shadowmoses]

I thought carbohydrates were used for energy to rebuild cells. That is why sleeping is an anabolic phase. Which is also why you are very low in carbs after you wake up.

Sleeping is only anabolic if you are in a calorie surplus, if you are in deficit you will use fat to carry out your repairing functions, but obviously they will be prioritised to more important tasks like maintaining your skin and hair etc,not building muscle which your body will see as useless when you are in a deficit of calories.....Thats why you can't gain much muscle when losing weight and in a caloific deficit,

SHadOW

[ozigal]

Sleeping is only anabolic if you are in a calorie surplus, if you are in deficit you will use fat to carry out your repairing functions, but obviously they will be prioritised to more important tasks like maintaining your skin and hair etc,not building muscle which your body will see as useless when you are in a deficit of calories.....Thats why you can't gain much muscle when losing weight and in a caloific deficit,

SHadOW

fat is not used to build muscle, proteins are since proteins contain amino acids which is what repairs and builds your muscle. Glycogen aids in fueling this process. Fat helps with maintaining slow absorption of your protein and carbs and yes with hair, skin, nails and maintaining healthy cells in your body.

[lowkey122]

The best way to understand dieting in my opinion is to know how and why your body burns fat for energy instead of carbohydrates (or muscle for that matter). If carbohydrates are the main source of energy, why is fat ever burned? If it is because there is no carbohydrates, then why is muscle used for energy when there is plenty of fat in storage? In other words, at what point in your body do you burn fat instead of carbs or muscle?

I've NEVER been able to get a straight answer on this topic. Some over simplify this with the calories in-calories out method. Others talk about insulin sensitivity/levels and glycemic index effecting fat storage and loss. Some say don't eat carbs in the pm, some say no saturated fats. Others say you need sat fats and who cares about egg yolks, etc etc etc.

What I've never been able to understand is muscle loss vs fat loss. How does your body distinguish? I've read it takes your body more energy to break down fat for energy, on the other hand protein is ready and available in muscles and easier to break down for energy which is why your body will eat away at muscle while not touching the fat around your stomach. Obviously glycogen is the most preferred source but when glycogen stores get low your body has to make a choice, muscle or fat?

People say no matter wether you're bulking or cutting, you should keep protein levels the same, just adjust fat and carb intake. What I don't get is if protein is preferred over fat, why wouldn't your body just use the whey, chicken and tuna you're feeding it every 2-3 hours for energy since it's easier for it to break down than fat? How does your body specifically choose to burn fat over protein or glycogen and if you know how that process happens, why not imitate that so you don't lose muscle?

[AphtaLyfe]

Glycogen is the body's storage of "fast" energy. The conversion of glycogen to glucose to energy is very quick compared to fat utilization.

*edit* "Fast" energy is used/needed when you need a large amount of energy in a short amount of time.

The reason why people recommend HIIT for individuals with higher body fat is because once glycogen is depleted fat(fatty acids) can be used to replenish the glycogen stores.

The reason why people recommend steady low intensity cardio for individuals with lower body fat is because the body will typically use more fat and less glycogen for energy.

The reason why people with low body fat should not do HIIT is because if your body has a low % of fat and a high % of muscle... the body will use what is most readily available... aka... muscle.

fat is not used to build muscle, proteins are since proteins contain amino acids which is what repairs and builds your muscle. Glycogen aids in fueling this process. Fat helps with maintaining slow absorption of your protein and carbs and yes with hair, skin, nails and maintaining healthy cells in your body.

Fat IS used to build muscle, both directly and indirectly. Muscles are cells too. Fat is needed to create hormones.(testosterone for example) Fat is also needed in order to expand the size of muscle cells.(or in rare instances the creation of new muscle cells)

During sleep a combination of fat and glycogen is used... I'm not 100% sure but I'm going to guess that its mostly glycogen. The thing is glycogen stores in the body will not last 8 hours if your body is actively using them, so there is probably some(alot?) of fat being used as well.

As for sleeping as an anabolic phase...Its anabolic because testosterone levels are highest when you are sleeping, which forces your body to be anabolic. (also the reason why steroid users have very little muscle loss even when doing extreme cutting)

[Viper3]

So besides doing HIIT training, what is the best way to force your body to use fat for energy instead of carbs or muscle?