Fruit would seemingly have a health halo. After all, munching on a piece of fruit is better than chowing down on a candy bar, right? Yet, there are sources that believe that eating too much fruit can cause weight gain and an expanding waistline. These folks are mostly low-carbers who limit the grams of carbs they take in per day, usually to no more than 50 grams.
Why is fruit being targeted as fodder for weight gain? After all, it comes in lots of naturally bright colors and we know that means they’re rich in phytonutrients that have health benefits. What’s not to love? The anti-fruit establishment points out that many fruits are high in sugar. Fruit contains both glucose and fructose, two forms of sugar that are processed by your body slightly differently. You’ve heard of high-fructose corn syrup, a manufactured form of fructose in a variety of highly processed foods. High fructose corn syrup is linked with an elevation in triglycerides and fatty liver, based on some studies.
Fruit and Weight Gain
So, why would fruit potentially lead to weight gain? We know that fruit isn’t high in calories, so you’d have to eat a lot of it to incur a calorie excess. Glucose, which fruit contains, can cause a rapid rise in blood sugar and a surge in insulin release, and we know high insulin states are more favorable for weight gain. What about fructose? Research links high fructose consumption with weight gain, but through a different mechanism.
Fructose doesn’t suppress appetite as much as glucose does, so you don’t feel as satisfied when you eat it. It can also disrupt the normal functioning of the appetite hormone leptin and contribute to leptin resistance. When that happens, you no longer get signals that tell you to stop eating. Leptin resistance also leads to a slow-down in resting metabolic rate. All of these factors can lead to weight gain.
Based on some research, fructose is linked with other health problems, including fatty liver. Unlike glucose, which all cells of the body can take up and use, only the liver can metabolize fructose. When you consume too much of it, liver cells get overwhelmed and turn fructose into fat. Unfortunately, this fat can build up in the liver. It can also cause a rise in uric acid, a problem that can lead to gout.
Should You Limit the Amount of Fruit You Eat?
If fruit contains fructose and fructose is linked with weight gain and obesity, should you purge the fruit from your fridge? Not so fast! Fruit isn’t JUST fructose. It also contains fiber and polyphenols and these two components change how your body responds to fructose. When you consume a piece of whole fruit, the fiber slows the absorption of fructose from the digestive tract so that your liver receives the fructose much more slowly and at a rate, it can safely handle. There’s some evidence that the polyphenols in fruit slow the rise in blood sugar that happens when you eat fruit.
Fruit May in Moderation May Lower the Risk of Health Problems
Most nutritional studies aren’t randomized-controlled, double-blind trials, the type that when well-conducted show cause and effect. Instead, they’re correlational studies that look at people’s dietary habits and how they correlate with certain diseases or health markers. These studies show correlation but not causation. For example, a number of studies link higher fruit consumption with a reduced risk of chronic health problems, particularly cardiovascular disease. But, this could be because people who eat fruit tend to be healthier in general.
Yet, there are randomized-controlled studies that link fruit consumption with a reduced risk of health problems. For example, a study published in Lancet found that participants who ate more fruit had lower blood pressure and higher levels of antioxidants in their bloodstream.
Plus, a study found that subjects who ate two pieces of low-calorie fruit daily for 3 months had lower blood pressure and better blood sugar control. They also had better HgBA1C values, a marker of longer-term blood sugar control. Correlational studies also show that fruit lovers have a lower risk of stroke. So, fruit appears to have health benefits and may help with blood pressure and blood sugar control, despite the fructose they contain. This shows the importance of looking at food as a whole rather than at its isolated components.
Are Some Fruits Better Than Others?
All fruit contains substantial quantities of vitamins, minerals, and phytonutrients. However, some fruit is higher or lower in natural sugar, including glucose and fructose. Fruit at the low end of the sugar spectrum is berries, and berries are some of the most nutrient-dense foods there are. So, you can enjoy the nutrient density that fruit offers with less natural sugar by treating yourself to berries.
Fruit at the higher end of the natural sugar spectrum include bananas, pears, pineapple, watermelon, and pomegranates. But, remember, these fruits are still low in calories and packed with nutrients. It’s doubtful you could eat enough of these fruits to get sufficient fructose to cause weight gain or other metabolic health issues.
But, avoid dried fruit and fruit juice. Both are a concentrated source of natural sugar, and fruit juice lacks the fiber you need to slow the absorption of the natural sugars in whole fruit.
The Bottom Line
Fruit, in moderation, is healthy food! However, if you’re diabetic or are struggling to lose weight, stick to lower sugar fruit, particularly berries. You’ll get all of the goodness that fruit offers, including lots of vitamins, minerals, and phytonutrients, with a minimum of natural fructose or glucose. Keep in mind that fruit is so low in calories that you’d have to eat lots of it to gain weight, but why not balance it out with more non-starchy vegetables? They, too, are nutrient dense and low in calories. Still, don’t be afraid of eating whole fruit, even if you’re trying to lose weight, but do it in moderation. A balanced diet is best.
References:
Harvard Health Publishing. “Abundance of fructose not good for the liver, heart”
Preventive Medicine. Volume 32, Issue 1, January 2001, Pages 33-39
The American Journal of Clinical Nutrition, Volume 76, Issue 5, 1 November 2002, Pages 911–922.
Lancet (London, England) [01 Jun 2002, 359(9322):1969-1974]
Complement Ther Clin Pract. 2013 May;19(2):97-100. doi: 10.1016/j.ctcp.2012.12.002.
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