Health experts and popular diet programs sometimes promote the free-fruit myth, where we can liberally gorge on bananas, grapes, and other medium—and high—sugar impact fruits while becoming lean, toned and healthy.
Unfortunately, that’s not always the case.
“But sugar from fruit is different than what you would get in a candy bar!” someone will occasionally say.
True, fruit comes nature-wrapped with fiber, nutrients, antioxidants, and other good stuff that helps buffer out its sugar load. That doesn’t mean excessive amounts of fruit can’t become problematic.
“Fruits contain antioxidants, vitamins and minerals, which is why eating a small amount of them is fine for healthy people,” says Dr. Joseph Mercola. “However, I would conservatively estimate that 75 percent of the population needs to restrict fruit intake, and this is directly related to its fructose content.”
Whereas experts once recommended fructose to diabetics because it didn’t raise insulin, we now know what it does do becomes far worse.
“Fructose was initially thought to be advisable for patients with diabetes due to its low glycemic index,” researchers say in a study published in the journal Physiological Reviews. “However, chronically high consumption of fructose in rodents leads to [liver and overall] insulin resistance, obesity, type 2 diabetes mellitus, and high blood pressure.”
Regardless what research and top experts say, the USDA MyPlate supports the unlimited-fruit idea, recommending at least five servings of fruit and veggies a day. “Any fruit or 100% fruit juice counts as part of the Fruit Group,” their website says. “Fruits may be fresh, canned, frozen, or dried, and may be whole, cut-up, or pureed.”
Sorry, but the nutrients and fiber in a banana, a cup of grape juice, or a quarter cup of dried raisins is miles away from what we get in kale, Brussels sprouts, or pretty much any non-starchy vegetable.
Fructose especially becomes an issue when fruit becomes unwrapped from its fiber in fruit juice concentrate, fruit juice puree, and yes, even fruit juice. These so-called healthy foods provide a major hit of fructose, which can create serious problems.
To understand why fructose gets a bad rep, consider how it behaves in your body. All sugars break down into glucose and fructose. Almost every cell in your body can utilize glucose, which signals your hormone insulin to deliver that glucose as a quick energy hit to your cells or store as glycogen in your liver or muscle cells.
Unlike glucose, fructose doesn’t raise insulin, a hormone that stores sugar in your cells or for back-up fuel. Fructose can also create leptin resistance where your brain doesn’t get the message to stop eating, contributing to obesity.
“Because insulin and leptin act as key afferent signals in the regulation of food intake and body weight…dietary fructose may contribute to increased energy intake and weight gain,” researchers in one study published in The American Journal of Clinical Nutrition wrote.
Even though fructose doesn’t raise insulin, excessive amounts can create insulin resistance. Because it beelines straight to our liver, fructose doesn’t signal satiety hormones, but it does put a lot of stress on that organ to metabolize, and fructose-induced nonalcoholic fatty liver disease has become a serious problem.
Over-consuming fructose leaves our liver no choice but to convert that excess fructose to triglycerides (fat), which finds a nice home around our midsections. A meta-analysis in the journal Atherosclerosis found excessive fructose could indeed increase triglyceride [fat] levels.
Fructose also creates a process called glycation, where sugar literally binds to proteins and “gums” them up. One study with rats in The Journal of Nutrition found long-term fructose consumption induces glycation and ages you more quickly.
How much fruit becomes too much to avoid fructose overload? One or two servings of low-sugar impact fruit, like a cup of raspberries, provide copious nutrients and fiber. Stick with berries, avocado, and other high-fiber, low-sugar impact fruits.
We want to be especially mindful about higher-sugar fruits (looking at you, grapes and mangoes), and especially steer clear of concentrated sugar bombs like dried fruit, high-fructose choices like “no sugar added” jam, and “healthy” juices. One popular green drink actually consists of mostly fruits and packed almost a whopping 60 grams of sugar in in a 15.2 ounce bottle, most of it fructose.
The good news is we can easily reverse these and other damages to reset our metabolism. “Remove [fructose], and the appetite control system goes back to working as designed and starts moderating the amount of everything you consume,” says David Gillespie in an interview about his book Big Fat Lies. “Slowly but surely, your weight returns to the normal weight range, and it stays there.”
I realize unlimited fruit is still considered healthy in some circles. Can excessive fruit create metabolic and hormonal havoc or am I making much ado over nothing? Share your thoughts below.
H Basciano et al., “Fructose, insulin resistance, and metabolic dyslipidemia,” Nutrition Metabolism (London) 2, no 1 (2005): 5.
GA Bray et al., “Consumption of high-fructose corn syrup in beverages may play a role in the epidemic of obesity,” The American Journal of Clinical Nutrition 79, no 4 (2004): 537-43.
SS Elliott et al., “Fructose, weight gain, and the insulin resistance syndrome,” The American Journal of Clinical Nutrition 76, no 5 (2002): 911-22.
D Gillespie, Big Fat Lies: How the Diet Industry is Making You Sick, Fat and Poor (New York: E-penguin, 2012). Kindle edition.
B Levi and MJ Werman, Long-term fructose consumption accelerates glycation and several age-related variables in male rats,” The Journal of Nutrition 128, no 9 (1998): 1442-9.
A Shapiro et al., “Fructose-induced leptin resistance exacerbates weight gain in response to subsequent high-fat feeding,” American Journal of Physiology: Regulatory, Integrative, and Comparative Physiology 295, no 5 (2008): R1370-5.
L Tappy and KA Le, “Metabolic effects of fructose and the worldwide increase in obesity, ” Physiological Reviews 90, no 1 (2010): 23-46.
MB Vos and JE Lavine, “Dietary fructose in nonalcoholic fatty liver disease,” Hepatology 57, no 6 (2013): 2525-31.
D Wang et al., “Effect of fructose on postprandial triglycerides: a systematic review and meta-analysis of controlled feeding trials,” Atherosclerosis 232, no 1 (2014): 125-33.
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