Fruit: Can it cause weight gain, diabetes, or fatty liver?

by | Nov 1, 2022 | Nutrition

Everyone has heard that fruit is healthy. But can too much fruit be the cause of weight gain, fatty liver disease, or even diabetes?

There are various reports circulating on social media and some of them may have a grain of truth. So let’s look at these three claims about fruit.

Fruit causes weight gain

The argument about fruit and weight gain is usually based in the Insulin obesity hypothesis. Insulin is a hormone that allows the body to store energy. Therefore, if we do not want to gain weight or even lose weight, we should keep its levels low. Fruit contains a lot of sugars, which increase insulin, and in addition, it is often sweet and tastes good.

While it is true that insulin is involved in storing energy in the body, it does not make sense for healthy people to monitor insulin and try to suppress it. This encourages people to follow low-carb diets, which is counterproductive, especially for those athletically inclined.

We know from studies that low-carbohydrate and high-carbohydrate diets work equally well for weight reduction and weight maintenance. [2] Some studies suggest that low-carbohydrate diets, while being just as effective or even more effective in the shorter-term, after a year they start to fall behind.

Additionally, fruit specifically is strongly associated with lower body weight.[1] It contains a lot of water, fiber, and, as a bonus, vitamins, minerals, and other health-beneficial substances.

If your goal is to manage or lose weight, it is best to eat fresh or frozen fruit instead of dried fruit.

But “What if I drink a fruit smoothie? That way I get a lot of sugar in my body quickly.”

We know that we can absorb liquid food such as fruit smoothies and juices faster than solid food. This can also result in a faster and higher rise in blood glucose levels.

Widely available new technologies such as CGM (Continuous glucose monitors), which allow users to continuously obtain information about blood sugar lead some users to worry about whether such fluctuations are healthy and do not lead to diabetes. In this case, it can be misleading. As long as the blood sugar levels don’t rise above a certain level, there is nothing to worry about. Chronic sugar status is a better market to look at. (HbA1c)

“Okay, but fructose intake is associated with fatty liver and fruit is a source of fructose.”

True again. In general, fruit contains about half of the sugars from fructose, and according to studies, it is associated with fatty liver. But it is necessary to look at where the fructose comes from. We will find out that the problem is not fruit, but various products and ultra-processed foods containing high amounts of it.

Fruit does not have much fructose and the first few grams get deactivated in the liver (about 5-6g). The concentration of fructose, another important factor of the metabolic switch, is not high. Fiber, vit.C, and other things slow down fructose release as well.
In the image below, you can see the foods and how likely they are to cause fatty liver.[3]

Too much of everything is harmful, but we don’t typically see people overeating fruit. The main factor driving health problems is being overweight.

Fruit is not only tasty and healthy but also helps in the fight against overweight, obesity, cardiovascular, and neurodegenerative diseases.

Analysis of 96 dietary studies found that the consumption of fruit was associated with reductions in risk for coronary heart disease, cardiovascular disease, total cancer, and all-cause mortality. The benefits were observed up to 800 g/day for all outcomes except cancer (600 g/day). Inverse associations were observed between the intake of apples and pears, citrus fruits, green leafy vegetables, cruciferous vegetables, and salads and cardiovascular disease and all-cause mortality, and between the intake of green-yellow vegetables and cruciferous vegetables and total cancer risk.[4]

Higher intakes of fruit and vegetables were associated with lower mortality; the risk reduction plateaued at ≈5 servings of fruit and vegetables per day.[5]

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  1. Mozaffarian, Dariush et al. “Changes in diet and lifestyle and long-term weight gain in women and men.” The New England journal of medicine vol. 364,25 (2011): 2392-404. doi:10.1056/NEJMoa1014296
  2. Ge L, Sadeghirad B, Ball GDC, et al. Comparison of dietary macronutrient patterns of 14 popular named dietary programmes for weight and cardiovascular risk factor reduction in adults: systematic review and network meta-analysis of randomised trials [published correction appears in BMJ. 2020 Aug 5;370:m3095]. BMJ. 2020;369:m696. Published 2020 Apr 1. doi:10.1136/bmj.m696
  3. He K, Li Y, Guo X, Zhong L, Tang S. Food groups and the likelihood of non-alcoholic fatty liver disease: a systematic review and meta-analysis [published online ahead of print, 2020 Mar 6]. Br J Nutr. 2020;124(1):1-13. doi:10.1017/S0007114520000914
  4. Aune D, Giovannucci E, Boffetta P, et al. Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality-a systematic review and dose-response meta-analysis of prospective studies. Int J Epidemiol. 2017;46(3):1029-1056. doi:10.1093/ije/dyw319
  5. Wang DD, Li Y, Bhupathiraju SN, et al. Fruit and Vegetable Intake and Mortality: Results From 2 Prospective Cohort Studies of US Men and Women and a Meta-Analysis of 26 Cohort Studies. Circulation. 2021;143(17):1642-1654. doi:10.1161/CIRCULATIONAHA.120.048996