Saturated fat and added sugars aren’t doing your midsection any favors

Think fat is fat and carbs are carbs? Think again.

Saturated fats may boost deep belly fat

Are some fats in foods more likely to end up as harmful visceral fat than as less-harmful subcutaneous fat?

To find out, Ulf Risérus, associate professor of clinical nutrition and metabolism at Uppsala University in Sweden, and his colleagues devised what some have called “the muffin study.”

“We had lean people eat, on average, three muffins per day on top of their usual diet,” he explains. That meant that each participant ate 750 more calories a day than he or she needed.

“We wanted a moderate—not an extreme—increase in calorie intake to represent the normal situation in the Western world, where most people gain weight after their 30s.”

Half of the participants got muffins made with a saturated fat (palm oil), while the other half got muffins made with a polyunsaturated fat (sunflower oil).

After seven weeks, both groups had gained the same amount of weight (about 3½ pounds). But there was a difference.

“The subjects who consumed the muffins baked with saturated fat gained more visceral fat and more liver fat,” says Risérus, “whereas there was clearly less visceral fat accumulation in the individuals who consumed the muffins baked with unsaturated fat.” Instead, those people gained more lean tissue.1

In his recent—but not yet published—study, overweight or obese people gained liver fat when they ate muffins made with saturated, but not unsaturated, fat.2 “So it’s clear that that was not a chance finding,” says Risérus.

What about monounsaturated fats like olive and canola oil?

“The evidence is not yet as strong as it is for polyunsaturates,” says Risérus. “But some studies suggest that monounsaturated fat is better than saturated. Polyunsaturated omega-3 fats from fatty fish also seem good, though the evidence isn’t as clear.”

Have a low-fat yogurt with nuts (unsaturated fat) instead of crackers with cheese (saturated fat).

His bottom line: “Replace some saturated fats from palm oil and butter, for instance, with a variety of mono- and polyunsaturated fats, mainly from plant sources like canola, olive, sunflower, and soybean oils and from fish.”

And, needless to say, don’t overeat. “If you gain weight, it’s difficult to limit fat accumulation,” says Risérus.

Sugars may boost liver & deep belly fat

Excess liver fat is a sign of trouble. “It’s associated with an increased risk for insulin resistance, type 2 diabetes, and liver damage,” says Kimber Stanhope, a researcher at the University of California, Davis.

Some researchers argue that a fatty liver also triggers insulin resistance, which can lead to diabetes.

“We still don’t know if increased liver fat is the cause or the result of insulin resistance,” says Stanhope. But even if a fatty liver doesn’t lead to diabetes, it can cause damage. “Over the long term, it can lead to non-alcoholic fatty liver disease and inflammation.”

“The prevalence of fatty liver is going up in both adults and children,” she adds. “Until recently, kids with fatty livers were rare.”

Clearly, the obesity epidemic deserves much of the blame. But in 2012, Danish scientists added a new wrinkle to the story.

They reported that overweight or obese people who were told to drink a liter a day of sugar-sweetened cola accumulated more liver and visceral fat after six months than those told to drink a liter a day of milk (which had the same number of calories), diet cola, or water.3

Have an orange (70 calories and no added sugar) instead of a Panera Cranberry Orange Muffin (480 calories and 10 tsp. of added sugar).

The fructose that makes up roughly half of both table sugar and high-fructose corn syrup may be the culprit.

”In a small recent study, men who were given 25 percent of their calories from fructose had more liver fat after nine days than when they got 25 percent of their calories from starches like bread, cereal, pasta, rice, and potatoes,” says Stanhope.4

“We need more studies to be sure, but it appears likely that sugars increase liver fat.”


Diabetes 63: 2356, 2014.
Obesity Rev. 17 (Suppl. 2): 51, 2016.
3 Am. J. Clin. Nutr. 95: 283, 2012.
4 J. Clin. Endocrinol. Metab. 100: 2434, 2015.

Illustration: © Dennis Cox/ Photos (top to bottom): © goodween123/ (left), © Moving Moment/ (right), © nipaporn/ (left), Panera Bread (right).

The information in this post first appeared in Nutrition Action Healthletter in January 2018.

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11 Replies to “Saturated fat and added sugars aren’t doing your midsection any favors”

  1. how in the world would a person know if they have excess liver fat?
    no mention of subcutaneous fat why is it in the diagram?

    1. Get tested for pre-diabetes & fatty liver, they seem to be a team, caused in some cases by medications, like Seroquel ! used for insomnia even in small doses it di this to me!

  2. I’ve been ordering Nutrition Action in hard copy for years and love this online copy, too. The information contained in both have been very helpful in my food decisions and are a part of my healthy lifestyle.

  3. This is my question also. It’s all well and good to have this information about making healthy choices, which I try to do, but how does the average person find out whether they have a fatty liver or whether dietary changes are actually having the desired effect?

  4. you mention “replacing sat fat from palm oil & butter with mono & poly unsat fat from plant: canola, olive, sunflower, soy, & fish” – question: whats
    with palm …its a plant ?

    1. Palm oil is from a palm tree. Plantations of palm oil nut trees are responsible for the cutting down of forests, resulting in the loss of habitat and near extinction of Orangutang, Lemurs, and other primates, for example in Madagascar. I avoid foods listing palm oil on the ingredients list, unless I know for sure that it is obtained from sustainable farms, not new growth. We are killing everything in our environment.

  5. This sounds like a good opening for a list of isocaloric “eat this, not that” snack bites.
    – 1 oz cheese vs 3/4 oz nuts (be explict about how many nuts this represents)
    – processed ingredient muffin vs whole grain English muffin with PB
    – etc etc etc
    Also, I’d like to hear about nutrient comparisons — not just the fats/added sugars, but the vitamins and minerals which naturally occur in the different foods used in these experiments. I sometimes wonder if its not the ingredient itself, but the lack of OTHER nutrients needed to process saturated fats/sugars in a more healthful way.

  6. Just go to your MD, they can easily test your fat levels in your liver. I get mine tested regularly. It’s simple blood work to start. I already have liver damage from fatty liver but I also am a long time diabetic. I have NASH, non alcoholic (scarred liver) disease. Checking your liver enzymes is a good start. They do MRI’s & some cat scans also biopsies as a last resort. There is such a thing as a fiber scan which is a special ultrasound which I’ve had as well. It does give a false positive or a higher than reality reading at times.
    Doctors will not do tests at all unless your blood work is off the charts for a prolonged period of time. Remember your liver regenerates so they only get concerned if your liver enzymes stay highly elevated for a long time. Best you can do is watch your sugars, exercise, eat healthy, laugh a lot, and really enjoy living your life no matter what condition you are in.

    My question is different. I was told by two hepetologists (liver specialists MD) in two different health systems and nutritionists in those units, never to eat non fat yogurt!!! They wanted me on whole milk milk & yogurt. They said non fat yogurt was such a scam. They remove the fat, then so companies have to fill it with something, so they fill it with milk sugars. Therefore, for those of us watching our sugars, carbs and how much work our livers must do, whole milk stuff is the way to go. I never had whole milk anything. My parents were health nuts. So at 55 yrs old I tried whole milk for the first time. It wasn’t that bad. Certainly the yogurt tasted a lot better. But I was wondering since you push nonfat yogurt a lot why you haven’t pointed out that nonfat yogurt has a lot more milk sugars? I know the fat in whole milk also slows the absorption of carb, sugars etc. So I know that’s why liver specialists (MD) recommend to Me this switch, as well. Just interested & wondering.

    1. Hi Natasha,
      Thank you for your thoughtful comment and question! It’s a common misconception that manufacturers add sugars to “make up” for the lost fat, but there is a negligible difference in the amount of sugars in plain low-fat and whole-fat yogurt. Here are some examples from Stonyfield Organic, whose low-fat plain yogurt has 12 g sugar/serving (, and whose whole-fat plain yogurt has 11 g sugar/serving ( Greek yogurt has even less sugar/serving because much of it is strained out. Sometimes flavored low-fat yogurts will have more sugar than their whole-fat counterparts, so we recommend sticking to plain.

  7. One thing to note in this article, the studies overfed individuals to measure the effect of the different fats on lipid deposition, an additional comment should have included that over consumption leads to weight gain. Better to keep the calories under control irrespective of the food (fat) source

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