FAT: Burn It or Store It. What Determines This?

The Grand Unified Theory Of Fat

You have heard by now that fat doesn’t make you fat, carbs make you fat. This seems confusing. Why wouldn’t fat also make you fat? Rarely is a cogent answer supplied for that one. Here’s the answer.Fat

The amount of fat you have is regulated to an ideal homeostatic set-point by the hypothalamus, a tiny but crucial brain that manages metabolism and energy expenditure.  If you have more fat than the hypothalamus thinks appropriate it will burn it, less and it will store it. The level it thinks is appropriate depends to some extent on your activity level and it’s perception of the seasons. Higher activity will somewhat lower the set-point, and you will store less fat,  and onset of winter will raise it. Fine, you think, so why does anyone ever get fat?

Well, there’s a catch, and it’s a big one. If insulin is high, this hypothalamic fat regulation apparatus is shut down, and fat is stored, not burnt. This includes both the carbs you just ate and any fat you consumed as well. Fat, in the form of triglycerides, also piles up in your blood. Now glucose is the only food that runs insulin up. So this is why carbs, especially sugar and starch, make you fat. They run your insulin up, block the fat regulation and put you in a fat storage mode. If you are a kid and can metabolize all those carbs without running up your insulin, then those carbs won’t make you fat. That’s why kids can get away with that sort of thing, but if those kids eat enough carbs, you get the childhood obesity epidemic.

This hypothalamic regulation is why the Atkins diet works well at first and why there is no more weight loss after a few months. Atkins is a very low carb diet. This causes the insulin to drop, which allows the hypothalamus to regulate the fat to its desired level. If there is excess fat, it will burn it off quite quickly. It actually burns it. You will feel hot and sweaty. This burning of fat yields the rapid weight loss this diet is famous for. As soon as the fat has burned down to the ideal hypothalamic reference level, fat is regulated. No more weight loss or gain.

With today’s social pressure to be forever skinny, many will not be pleased with the fat level their hypothalamus has chosen for them. Eating less will not work well. Your hypothalamus will fight it tooth and nail. It will lower your energy level, your mental acuity, your creativity, your immune system, cellular repair level, anything to hang on to that precious fat. You will be irritable, anxious, and depressed. If you starve yourself enough, you can lose more weight, but you will effectively become a zombie.

Why is the hypothalamus so enamored with fat? And why does it shut down the fat burn when you eat a bunch of carbs? Fat is your reserve fuel. As far as the hypothalamus is concerned, we are all still hunter-gatherers. If we run out of food, that stored fat is our lifeline. So it will let other stuff slide in order to hold on to it.

But why let the carbs derail the regulation process? Recall that hunter-gatherers ate little or no starch, maybe some honey when they lucked into it, and fruit in season. This meant carbs were a summertime thing. Since a long ice age winter was soon to follow, it makes sense to store up all that sugar as fat. So it does.

The hypothalamic set-point for the fat storage is genetic. The northern hunter-gatherer populations needed better fat preservation skills. Where did you come from?



  4 comments for “FAT: Burn It or Store It. What Determines This?

  1. Sri
    February 14, 2015 at 3:49 am

    Thanks for this Post Doc. I was wondering why I lost a lot of weight, and then the weight loss stopped abruptly and body maintains the same weight irrespective of my exercise/nutrition changes to influence it.. I came to a conclusion that the body has its own regulatory mechanism that operates independently, now I understand how it works.

  2. Sri
    February 14, 2015 at 3:52 am

    Feedback about the new design change…
    Its is very good, but 2 issues,

    1) The font size of the content in the sidebar could be lesser than that of the content in the middle, it would reduce distraction while reading

    2) Would really help if you could add a Recent Comments widget to the sidebar

  3. Vinayak
    April 6, 2015 at 7:18 am

    Great article! And I have a few questions:

    1) Why does higher activity lower the hypothalamus-set ideal fat level? Higher activity should mean you’re going to need a lot of fuel in the near future. No?

    2) How do you determine what your hypothalamus has decided to be your ideal fat level? I guess you can go on a no-carbs diet for a while and check the fat level you reach. But say you’ve always had some fat around your belly ever since you were 7 years old, does it mean perhaps the belly fat is being regulated by your hypothalamus and that it’s going to be impossible to lose it?

    3) What are the ways to lower the hypothalamus governed fat level? I guess increasing activity level is one, but are there any others? Also, apart from aesthetics, are there any benefits of doing so?

  4. Charles
    January 29, 2016 at 7:15 pm

    Very interesting information. Something that is of great interest to me, as I have cardiovascular problems. I am looking for ways to reverse the atherosclerosis.

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