Does Eating Fat Make Us Fat?

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

Originally Posted on the Diet Doctor Blog 

3 thoughts on “Does Eating Fat Make Us Fat?”

  1. Dr. Bret,

    I appreciate the way you write with humility balanced with quiet determination to help people learn how to live more healthy lives.  Thank you.  How do you help and support the people in your life that you love?

    I have come to understand the habits that foster health and wellness in such a different way than what i was taught.  Is it possible to suport those that i love to more closely examine what we’ve been taught without being seen as foolish?  I am living a LCHF lifestyle and those around me, who i know love and care about me, tell me my health is going to suffer and that i’m not acting wisely.  Sometimes i feel i have to hide the eggs that i enjoy, the olive oil i pour on my vegetables and the cheese i add to my salad.

    Do you have any thoughts you would feel comfortable sharing on this topic?

    Thank you for providing us all with your wisdom on nutrition and good health.


    denise myers


    1. Thank you for your comments Denise. That certainly is a tricky situation that requires a gentle solution. I find the best approach is gentle education. Sharing a video, a blog, or a podcast that you think might resonate with the individual is a great place to start. I would suggest not being advesarial about it, but rather approaching it as “there is more than one way to look at this and here is something I found compelling, I am curious what you think about it.”  Slow and steady wins the race!

  2. If that is the same study that I read, in addition to being fed high fat, the mice were genetically altered: missing ApoE.

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Bret Scher, MD FACC

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