Is Fruit Bad News for Weight Loss?

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Fruit got a really bad reputation when the low-carb movement started to take off. Fruit had its image badly bruised in the past few years, as more and more weight-loss experts tagged fruit, fruit juice, and soda as dietary sources of unnecessary sugar. It didn’t help that the particular sugar found in fruit—fructose—is the main ingredient in high fructose corn syrup (HFCS), one of the undisputed dietary demons of the past two decades.

The Truth About Fruit

So let’s back off a bit and take a serious look at fruit, which truly is one of the great health bargains to be found. It’s loaded with fiber, phytochemicals, flavonoids, vitamins, and minerals. It’s relatively low in calories. The anthocyanidins in berries and cherries (and other colored fruits) are highly anti-inflammatory (cherries have long been a traditional remedy for gout, for just that reason). Apples are loaded with quercetin, a potent anti-inflammatory compound, while blueberries are loaded with pterostilbene, an activator of longevity genes similar to the resveratrol found in dark grapes and red wine. And grapefruit and grapefruit juice are associated with weight loss, according to a landmark study at the Scripps Clinic.

The Carb Connection

One of the epic nutrition discoveries of the past 25 years or so was the fact that hormones drive weight gain. And food has a hormonal effect, particularly, but not limited to, its effect on insulin, the “fat storage” hormone. Foods high in sugar—or foods that convert to sugar quickly, such as grains—raise blood sugar quickly, which signals the pancreas to produce insulin. When blood sugar rises quickly and frequently (as it does on high-carb diets), the body produces more and more insulin, and it’s increasingly likely that the cells will start to ignore it. This condition—known as insulin resistance—is a forerunner and promoter of diabetes, obesity, and even heart disease.

Enter low-carb diets. Since insulin responds most dramatically to carbohydrates, it was thought—correctly—that the best way to modify insulin levels was to reduce the foods that create high insulin. Since sugar raises insulin more than any other “food,” foods with a lot of sugar (such as fruits, desserts, and cakes) and foods that convert to sugar in a New York minute (like grains) became the culinary equivalent of “persona non grata.”

Fructose: Friend or Foe?

Fructose, the sugar naturally found in fruit, presents particular problems of its own, independent of weight gain. Fructose actually doesn’t raise blood sugar directly—which is why, in much less enlightened times, it was recommended as the “perfect” sweetener for diabetics (it is most definitely not that).

Fructose either gets converted to glucose or goes directly to the liver via the portal vein, where—in large amounts—it causes all kinds of metabolic mischief, increasing triglycerides and contributing to obesity, high blood pressure, and diabetes (in animal studies).

It’s also a direct cause of non-alcoholic fatty liver disease. Diets very high in fructose are, frankly, bad news.

But there’s a critical distinction between the fructose you’d find in HFCS, and the fructose that’s found naturally in fruits.

The fructose found naturally in foods such as apples is surrounded with fiber and water, and comes along with a big helping of other beneficial nutrients. You’d have to eat an awful lot of apples to equal the amount of fructose found in just one HFCS-sweetened Pepsi.

In short, there’s a big difference between consuming small amounts of fructose from fruit on the one hand, and extracting that fructose, making it into a concentrated syrup (HFCS), and then adding it to just about every food in the grocery store on the other.

The Bottom Line

While concerns about the naturally occurring fructose in fruit may be a bit overblown, fruit still doesn’t completely get a free pass—at least not for everyone. For people who are very carb sensitive (for instance, those who have extreme difficulty losing weight), it’s probably a very good idea to cut back on fruit if not totally eliminate it for a while. That’s the reason stricter weight-loss programs such as Atkins, the South Beach Diet, or the Dukan Diet eliminate fruit for the first couple of weeks (the “induction” period of the diet).

And if you’re on a ketogenic diet—an increasingly popular option these days—fruit will knock you out of ketosis pretty quickly, so it’s best to avoid fruit in this case.

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