Carb vs. fat metabolism – the Dr. Ted Naiman hydraulic model


What happens in your body when you eat fat or carbs? Here are more awesome and simple illustrations from Dr. Ted Naiman, an “über-geeky mechanical hydraulic model of metabolism”.

Above you can see what happens when you eat a low-carb, high-fat diet. Your body gets its energy from the vast fat stores (in blue, to the right).

But what happens when you add carbs?

Some carbs


A standard American high-carb diet


In this third image the body mainly runs on carbs, and the fat stores start filling up with… fat. If you make sure to eat regularly, never fasting, you’re pretty much guaranteed to end up with quite large fat stores eventually.

As you might already have guessed – a great way to avoid the dreaded case #3 is to eat a real food, LCHF diet.

Top videos with Dr. Naiman

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  • Diet Doctor Podcast #40 with Ted Naiman
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    Hyperinsulinemia - what insulin does in your body
  • Becoming a low-carb doctor
  • Too much protein is better than too little

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  1. Pierre
  2. Simon Thompson
    It is Uber Geeky indeed. I like how the model shows how we can move from mixed CHO/Fat oxidation to either burning mostly CHO for energy or Fat for energy (exogenous or endogenous) by signalling using the amount of CHO in the diet. I realise that fat oxidation is preferable due to it being a "Cleaner" burning fuel.
  3. Bob Niland
    That art is a very nice model of the metabolic consequences, but would be more useful if the left vertical axis had actual intake, or marker measures.

    Replacing the 1x…4x with daily net carbs of:
    might do the trick, with 50g net carb aligned at the "2.4x" level, if we agree that it's the ketotic/glycemic border. This scale people can learn to directly apply to the Nutrition Facts for foods.

    An alternative left vertical scale might be HbA1c, with 5.2% at the "2.4x" level. Postprandial BG and fasting insulin are other candidates, but all these latter require running tests, which is a bit late in the recipe cycle.

  4. Apicius
    How cool! Love it!
  5. Steve
    Thank you for the narrative. I studied this when Ted tweeted it last week but it didn't click. Showing the different states makes it easier to understand.

    Ted, for a bonus... Can you depict when the fat stores "fill up" (cells stop responding to insulin) and the HbA1c rises and glucose spills out the kidney (T2D)? Perhaps a pressure gauge (representing HbA1c) and a pressure relief valve connecting to the kidneys?

  6. Nate
    How fun! As an engineer, I can't help wanting to tinker with it.

    How about making the stopper that prevents fat from being burned longer for those that are not adapted to burning fat. Then there would be a time when the glucose has run out but the fat is not available to burn. Thus, representing for the mainly glucose burners, the sudden hunger that they experience three or so hours after eating. It would also represent the lack of energy or fuel that keeps people on the couch and not out dancing or whatever.

  7. Apicius
    Ok, I was not going to comment on the engineering aspects, for fear of looking like a geek. But, since I see some fellow engineers chimed in with their enhanced designs, I too would like to give my two cents. (Yes, I am an engineer, in case you were wondering.)

    I think check valves are vital to the design, or else you get serious back-flow (fat into carb, or carb into fat) especially when hydraulic pressure (height) is significantly higher in the opposite compartment.

    The combined flow (fat and carb mixed stream) should flow into a liquid-liquid separator, whereby fat floats to the top and carb settles at the bottom (just like the separation of vinegar and oil...after shaking them together in a jar, they separate in a few seconds). With a tapped slip stream at the top of the separator vessel (for fat) and another nozzle tapped at the bottom (for carbs), they get diverted to the correct "burner" (burn sugar, or lipolysis). An inline meter that can detect interphase levels of the two immiscible fluids, such as a conductivity meter, can be interlocked in the start and shutdown of either burner using simple PLC control. Or you can go old school and just install a mechanical float at the interface.

    The fat compartment is not designed correctly. Because of its square design, the lower the fluid level, the lower the hydraulic pressure, and less energy delivered to the body. This implies fasting causes metabolic slow down while in ketosis. Which is incorrect. A better design would have the fat chamber tapered (triangle shape) with triangle point at the bottom and large triangle base at the top. This provides higher fluid level and higher hydraulic pressure, and strong energy flow through ketosis. Keeping in mind that fat has a lower specific gravity than carb, this becomes very important.

    The fat chamber should have floats that activate a cascade of problems when fat inventory gets too high. First level triggers abdominal fat. Second level triggers type 2 diabetes. Third level triggers Alzheimer's.

    Ok..I will stop here. I could geek out forever and ever.

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