Is fructose to really to blame for rising rates of obesity? How much fructose can you safely consume?
And there are no whole foods that contain only fructose. For that matter, except for the pure fructose sweetener that’s made for diabetics, I can’t really think of any processed foods that contain only fructose. Virtually all foods that contain fructose—including fruit and even high fructose corn syrup—also contain other sugars, such as glucose, maltose, galactose, sucrose, and/or lactose.
Many of the concerns that people have about fructose would only be valid in the context of a 100% fructose diet. For example, while it’s true that fructose does not trigger the release of hormones that signal satiation (or fullness), those hormones are triggered by other nutrients in foods that contain fructose. What’s more, these appetite control hormones are not the only things that influence your sense of satiation. As I talked about in my show on how to eat less without feeling hungry, your stomach also has special receptors that can sense when your stomach is full—sending signals to your brain to stop eating. These sensors respond the same way no matter what type of nutrients are in that food.
My point is that the facts about how a molecule of fructose is metabolized don’t tell us much about the realities of how foods containing fructose affect the body. The foods you eat contain a lot more than just fructose—and digestion involves a lot more than a single metabolic pathway.
The Dose Makes the Poison
The other problem with many of the charges against fructose is that they are missing two important words: “excessive consumption.” Fructose does not cause weight gain, Type 2 diabetes, and metabolic syndrome. Excessive consumption of fructose might. But again, excessive consumption of fructose is invariably accompanied by excessive consumption of other things as well.
A primary source of both fructose and glucose in the modern diet is soft drinks. Our intake of soft drinks has more than doubled in the last 30 years. And I do believe that immoderate soda consumption is an underlying factor in the rising tide of obesity, Type 2 diabetes, and metabolic syndrome. But I don’t see how we can lay the responsibility for that exclusively at fructose’s door.
Remember, we don’t consume fructose by itself. If you’re consuming enough fructose to be risking fatty build-up in your liver, you’re also consuming enough glucose to put you at risk of insulin resistance, and enough excess calories to make you gain weight. In other words, we all know that consuming too much sugar has a number of harmful effects on the body. Overstimulation of the fructose pathway is just one of the many ways in which excessive sugar consumption wreaks its havoc.
But it does not necessarily follow that fructose is toxic at any dose. And it certainly doesn’t follow that you have to avoid fruit in order to lose weight.