Are Some Fruits More Fattening Than Others?
It’s time to clear up some confusion about fruit, sugar, fructose and how this all fits together into a healthy diet.
Monica Reinagel, MS, LD/N, CNS
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Are Some Fruits More Fattening Than Others?
It’s January and that means there’s a new crop of diet books out. You’d think we’d have learned by now that the next diet gimmick is not going to be the answer to our weighty woes. Believe me, the reason 2/3 of the population is overweight is NOT that no-one has yet written the right diet book.
But hope springs eternal, as does the January crop of New Year New You offerings. I was reviewing one of them this week and came across the claim that avoiding certain fruits can help you lose weight.
Specifically, the author recommends staying away from fruits that are high in fructose because, he explains, fructose is converted by the liver into fat. The high-fructose fruits on this author’s hit list include bananas, pineapples, grapes, and watermelon. Good “low-fructose” fruits include citrus fruit, berries, melons, and stone fruits like peaches.
I think we need to clear up some confusion about fruit, sugar, fructose, and how this all fits together into a healthy diet. (For one thing, some of the alleged high-fructose fruits have less fructose than the so-called low-fructose fruits…but I’m getting ahead of myself.)
When It Comes to Sugar, Fruit Is Not the Problem
The amount of sugar in the typical Western diet is definitely a concern. Health authorities recommend keeping added sugars to no more than 5% to 10% of calories (which works out to 100 – 200 calories or 25 – 50 grams of sugar per day).
However, this guideline applies to concentrated sweeteners that are added to foods; things like sugar, honey, and maple syrup. We generally aren’t worried about the sugar that you get from whole fruit.
See also: Ask the Diva: Does the Sugar in Fruit “Count” as Sugar?
For one thing, the natural sugars in fruit come packaged with other valuable things. Vitamins, minerals, and phytochemicals in fruits add nutrition to the diet. But whole fruit also contains fiber and water, two features that help provide some natural portion control.
See also: Is Fruit Good For You?
Just think about how many apples you might eat at one sitting compared to how many cookies you might be able to polish off. When it comes to filling up on fewer calories, apples definitely take the cake (pun intended).
Some of this natural portion control disappears when fruit is juiced and/or dried. Most of us would be hard-pressed to eat more than two whole apples. But it wouldn’t be that hard to consume the equivalent of 4 or 5 apples if we were drinking apple juice or eating dried apples.
I usually recommend limiting your fruit intake to 2 to 4 servings a day (depending on your size and how active you are). And I definitely advise prioritizing whole fruit over fruit juice and dried fruit. (While consumption of whole fruit is associated with a decreased risk of Type 2 diabetes, consumption of fruit juice is associated with increased risk.)
Is Fruit Too High in Sugar?
When we’re talking about excess sugar in the diet, fruit is generally not the problem. That said, the amount of sugar in various types of fruit ranges. Cranberries have almost no sugar. Dates are almost nothing but sugar. Choosing fruits that are lower in sugar might be a way to enjoy a little more fruit without quite as much sugar.
Here’s a table showing the amount of sugar in several common types of fruit. For a more detailed, interactive chart, see this post on Nutrition Over Easy.com
There’s definitely a big difference between unsweetened cranberries (just 5 grams per cup) and dates (86 grams per cup). But most fresh fruits fall in the more moderate range of 10 to 25 grams of naturally-occurring sugar per cup. Interestingly, pineapple (one of the author’s no-no fruits) and grapefruit (one of the yes fruits) both contain 16 grams of sugar per cup. Meanwhile, watermelon, which this author considers to be too high in sugar, has just 10 grams per cup.
What Kind of Sugar Is in Fruit?
So far we’ve been talking about total sugar. Let’s talk about what specific types of sugar fruit contains and how that might affect you.
Fructose means “fruit sugar.” But fructose is not the only kind of sugar in fruit—or even the primary type. Fruit contains fructose, glucose, and sucrose in varying amounts, along with tiny amounts of other sugars. In fact, most fruit contains a bit more glucose than fructose.
And why might the amount of fructose and glucose matter? Because these two sugars are metabolised differently. But again, misunderstandings and misperceptions abound.
Glucose is absorbed more directly into the bloodstream, which means that it raises your blood sugar relatively quickly. This is not necessarily a bad thing. The reason that athletes use glucose-based gels and goos during endurance sports is that they will quickly provide energy for fatigued muscles.
Fructose, on the other hand, is not absorbed directly into the bloodstream. Instead it is processed in the liver. But this is not necessarily a bad thing. In fact, fructose is often recommended for diabetics precisely because it is a natural sugar that will have minimal effect on blood sugar. Fructose also tastes quite a bit sweeter than glucose so it provides more sweetness for less sugar and fewer calories.
Is the Sugar in Fruit Converted to Fat?
It is not true that all fructose is converted directly to fat in the liver. Some of it is converted into glycogen, a stored form of energy used to power your cells and muscles between meals, when your blood sugar is lower. As with all other nutrients, the amount of energy that is stored as fat depends on how much total energy you’re taking in vs. how much you’re using up. If you’re relatively active, a lot of the fructose you take in will be used to replenish liver glycogen stores.
If you are taking in a lot more calories than you are burning, they’re going to get stored as fat. But in the big picture, it really doesn’t matter all that much whether those excess calories are coming in the form of glucose, fructose, starches, or fats.
Can Too Much Fruit Hurt Your Liver?
It is also true that overwhelming the liver with huge amounts of pure fructose—as in some of the studies that are frequently cited to stoke up anti-fructose hysteria—can create big problems, including liver damage. But you are unlikely to be getting huge amounts of pure fructose from eating two or three servings of whole fruit each day—even if you are taking your life into your hands by eating bananas.
One of my favorite ways to eat bananas these days is frozen and blended in my food processor with a teaspoon or two of unsweetened cocoa powder into a frozen yogurt like consistency. If you’ve never tried this, you might be amazed just how delicious and satisfying a dessert this makes—and all for about 100 calories and zero added sugar or artificial sweeteners. If that’s one of the “worst” fruits you can choose, I’d say that we probably have better things to worry about.
The Bottom Line on Fruit and Fructose
Diets that are very high in sugar are a problem—for a number of reasons. Eating large amounts of sugar will flood the body with both glucose and fructose—and each of these are problematic in their own way. Too much glucose eventually impairs blood sugar metabolism. Too much fructose eventually harms the liver. Taking in a lot of sugar can also lead to taking in too many calories, and this always leads to weight gain and fat storage.
But, as they say, the dose makes the poison. Something that may be harmful in high amounts may be harmless—or even beneficial—in small amounts. And in the context of an otherwise healthy and calorie-appropriate diet, the amount of sugar, glucose, and fructose that you will get from a couple of servings of fruit is not going to give you diabetes, liver damage, or turn your body into a fat storage factory—no matter which type of fruit you choose to enjoy.
About the Author
Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes’ most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation’s leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.