Does eating fat make us fat?

Mouse and cheese. Rodent vector Illustration

Does eating fat make us fat? According to a new article in The New York Times, it just might. With a heavy emphasis on “might.”

The New York Times: Which kinds of foods make us fat? (Paywall)

The article is based on a trial published in Cell Metabolism over the summer, which concluded that feeding mice up to 80% calories from fat causes weight gain. The same was not seen with higher levels of carbs or sugar intake.

Does this end the debate on what make us fat? Does this prove Gary Taubes and all the low-carb pioneers wrong?

Of course not. For starters, this was a study of mice. So, if you have pet mice, then you should definitely pay attention.

The bigger question, however, is does this trial apply to humans? I would argue absolutely not.

Here is what they found. The mice that ate a higher percentage of fat calories ate more total calories and gained more weight. They also found changes in the mice brains with increased gene expression of serotonin, dopamine and opioid receptors — the so-called “reward” receptors. Simply put, that means the mice found the fat so pleasurable, they ate more calories than any of the other mice and they even increased their reward-signaling pathways to match the pleasure they were experiencing.

Here’s the crux of the problem. Humans do the opposite. That’s right. The exact opposite. A review of 23 randomized trials showed that low-carb, high-fat subjects lost more weight than low-fat subjects, plus trials show low-carb, high-fat subjects experienced less hunger and ate fewer calories than low-fat subjects.

What about the reward center upregulation? In humans, that clearly happens in response to sugar, not fat. Once again, the exact opposite of the findings in the mice study.

The biggest take home from this study, therefore, should be the cautionary tale of using a mice study to predict human behaviors. This is especially true when we already have human studies showing the opposite effect. Low-carb diets help us eat less and lose more weight, and sugar lights up our reward centers like a Christmas tree. We don’t need mice studies to tell us that.

Thanks for reading,
Bret Scher, MD FACC


Could a keto diet increase the risk of diabetes (if you’re a mouse)?

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  1. Alain
    You should have asked what kind of fat they used.
    Because, for a lot of people they are the same.
    Reply: #5
  2. Robert Luciano
    It seems that the author of the aritcle is completly ignoring the physiology of lipid digestion...lipids enter the lymphatic circulation and are then dumped directly into bloodstream via the inferior vena cava...this is completely different than how carbs are digested...something all low carbers seem to conveniently forget
    Reply: #3
  3. CLG
    I would expect the body to process different foods differently your point?

    I have never had a weight problem other than being about 12kgs over my weight from my early 20s. Turns out my body didn't like my high carb diet, which I thought was good for me. I found out I had type 2 diabetes at 48 despite lots of regular running and a healthy low fat diet. I really tried to avoid fat. I have been over a year on low carb now. I lost that extra 12kgs super easy and have been rock steady weight wise since. I feel great and my lipid profiles come up great and my blood glucose levels are totally normal. I am not taking any drugs.

  4. Dan Quibell - Keto Weight Loss Coach
    Fat can absolutely make you fat if you eat in a caloric surplus. Been keto for 5 years and plan on doing so for the rest of my life.

    I have lost 90 lbs, cured my gout and lowered my blood pressure from 153/90 down to 108/66.

    I now teach keto for weight loss, the most common newbie mistake I see is people drinking BPC’s and eating fat bombs when trying to burn bodyfat. Fat isn’t a free for all. They can be either used or stored as bodyfat quite easily. Protein should be a focus for satiety and fat as needed for energy but at a minimum so we burn bodyfat instead of dietary fat.

    Caloric deficit is still needed to burn bodyfat & keto is PERFECT for this as it’s a very powerful appetite suppressant and also with the reduction of carbs so low we are forced to be efficient fat burners, we decide if that is dietary fat or if it’s bodyfat.

  5. Malcolm Sargeant
    All the types of fat that you would not want to eat anyway.
  6. Laurie
    What is a BPC DRINK ?
  7. Dorothy
    BPC = Bullet proof coffee. Typically made with butter, coconut oil and MCT oil.
  8. Laura Stirimin
    Mice traditionally eat grains, so the studies are not correct, using mice for tests on human nutrition is TOTALLY wrong!!!!

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