Food & Wine

Here's the Skinny on Low-Fat Diets

No one could explain why all the women were so fat.

In 1951, physiologist Ancel Keys studied the population of Naples, Italy. He found that among the city's working class, intake of fats was very low... and they had lower instances of heart disease. He concluded that low-fat diets lead to healthy hearts, and thus the modern-day mantra of "low fat is best" was born.

But Keys failed to mention two important points:

First, the diet of these workers consisted of little more than bread, pasta, coffee, wine, and olive oil. They only consumed lean meat (like fish) once or twice a week. That's because at the time, most of southern Italy faced widespread poverty. Meat was expensive... Malnutrition was rampant.

Second, despite working long hours every day and eating a Spartan diet... many of the women were significantly overweight.

The same study Keys used to promote his low-fat fad actually points to why carbohydrate-heavy diets lead to weight gain and other issues associated with obesity – like diabetes.

Cue Dr. Robert Atkins, who in 1972 published his first book Dr. Atkins' Diet Revolution. His idea of cutting back on carbohydrates to lose weight initially earned ridicule from the medical world. But over the past two decades, more and more research supports his theory. Authors like Gary Taubes and Dr. David Perlmutter have built success arguing similar principles.

You've even heard my own take on it: Avoid the "white killers." That means white bread, white sugar, and white rice.

Still, even in today's grocery store, we're facing the same problem... Low-fat foods are full of overprocessed sugars. Eating these foods creates a vicious cycle that perpetuates hunger. And as we get hungrier, we eat even more and gain weight.

And today we've got an added problem: Stress. All the stress of the year from the pandemic, economic shutdowns, unemployment, wildfires, protests and looting – just to name a few – makes us crave foods high in carbs and sugar. So we're struggling with those extra pounds. That's why we need to take a hard look at what's really going on...

It's All About Your Hormones

It's much more complicated than Keys explained.

For decades, I've heard the medical theory that to lose weight, you need to burn more calories than you take in. To be honest, calorie counters drive me nuts. The problem is more complex and lies in the balance of food types and how our individual bodies react to them.

When we eat food, our bodies release the hormone insulin. You're probably familiar with this in the context of diabetes. Insulin helps glucose (the sugar we get from food) get to our cells, where we either burn it for energy or start to store it.

Here's the thing... when insulin levels get abnormally high (after we eat a lot of glucose-heavy food), we store fat in our cells. When insulin levels fall, we take that fat out and our bodies burn it for energy.

As a side note, estrogen also plays a role in regulating fat storage in our cells. This might have factored into the obesity of the working-class women Keys studied.

And the biggest source of glucose is carbohydrates. Specifically, refined carbohydrates (like white bread), cereal grains, flour, starches (like potatoes), and sugar... including high-fructose corn syrup. Worse, processing removes the naturally satiating fiber in these foods, meaning they leave us feeling less full.

Normally, our bodies break down carbs to make glucose. We use glucose for energy. When we don't eat carbs, our bodies will break down fat. When fat breaks down, it creates an acid called a ketone (in a process called ketosis).

The ketones act as energy units that feed your body. They travel through your bloodstream to muscles. This is actually how you maintain energy when you fast.

Some folks try to jumpstart this process by following so-called ketogenic diets (similar to low-carb diets). These are popular for folks trying to lose weight by breaking down stored fat. Typically, these are high-fat, low-carbohydrate diets.

The thing is... ketogenic diets work, and they do help people lose weight. But they're extremely difficult to maintain over a long period of time.

The point is that 1) carbs are the real culprit in weight gain and 2) you don't have to avoid all fats. In fact, you should eat some fats because of their health benefits.

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What We're Reading...

Here's to our health, wealth, and a great retirement,

Dr. David Eifrig and the Health & Wealth Bulletin Research Team
October 27, 2020