Updated 20th June 2022

Low-fat foods: The truth

Low-fat yogurts, spreads, chips, mayonnaise, sauces, cereals, and sides — the list goes on. If a product typically contains fat, you can guarantee that a food manufacturer somewhere is marketing a low-fat version.

In this article, we’ll take a look at low-fat products. We’ll ask whether they’re really good for you and how this obsession with low-fat produce started.

Before we get going, it’s worth noting that many fresh foods are naturally low in fat, such as fruits and vegetables.

These foods are healthy, of course. But in this article, we’re focusing on manufactured, processed, or ultra-processed low-fat products.

At ZOE, we know that the key to good health is eating a wide range of natural, fresh produce, including plenty of plant foods. However, we also know that everyone responds to food differently.

If you’d like to learn more about which foods are best for your body, start by taking our free quiz.

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How did the low-fat trend begin?

The Western world’s obsession with avoiding fat has a long history. By the late 1800s, dieting and the pursuit of a slender body were starting to become popular in the United States. As a telling sign, public weighing scales first appeared in the 1890s.

At that time, people knew that fat contained more calories than an equivalent weight of protein or carbohydrates; so fat was the obvious food component to avoid.

In the 1920s, as fashions became more revealing, the desire to attain the “perfect” body shape intensified.

Initially, low-fat and low-calorie diets were mostly promoted by magazines and word of mouth. However, by the middle of the 20th century, the medical profession stepped in.

At that time, coronary heart disease was the largest killer of people in the U.S., so doctors were keen to identify risk factors. As scientists began to investigate, the diet-heart hypothesis was born.

The diet-heart hypothesis

The diet-heart hypothesis states that diets high in saturated fats and cholesterol cause coronary heart disease. Therefore, limiting fat intake would reduce heart disease risk.

Following the latest research, the American Heart Association recommended that individuals most at risk of heart disease reduce their fat intake. But they also made it clear that evidence for the dietary fat-heart disease link was not yet conclusive.

The low-fat ideology started ramping up in 1977 when the U.S. Senate's Select Committee on Nutrition and Human Needs published the “Dietary Goals in the United States” report.

The document explained that too much fat, sugar, and salt are directly linked to heart disease, cancer, obesity, and stroke.

Then, in 1983, a long-term study concluded that obesity was an independent risk factor for heart disease. Because experts believed that a low-fat diet would help people with obesity lose weight, the diet-heart hypothesis received a boost.

Although still a theory, medical professionals and public health bodies embraced the hypothesis. Increasingly, dietary fat was declared the single most important cause of obesity and heart disease.

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And in 1992, the United States Department of Agriculture (USDA) released its first “food pyramid,” which helped enshrine fat as the bad guy. 

Losing weight can be challenging, and many factors play a part.

For instance, ZOE scientists have shown that the billions of bacteria living in your gut are vital for good health. We've identified 15 “good” gut bacteria associated with positive health measures and 15 “bad” gut bacteria linked to worse health, including excess weight.

If you'd like to learn about your gut microbiome and how to boost your “good” bugs, you can take this free quiz today.

The role of food manufacturers

Initially, food manufacturers were deeply concerned about how fat was rapidly becoming the bad guy. They knew that a product with much less fat was likely to be much less tasty.

But it wasn’t long until they spotted a lucrative opportunity — they simply replaced fat with sugar.

Throughout the 1980s and 1990s, grocery shelves were stacked high with low-fat products containing just as many calories as their full-fat predecessors. 

Because these foods were marketed as “healthy,” consumers snacked freely, believing they were eating guilt-free pleasures. According to some experts, the boon in reduced-fat foods probably added to the growing obesity crisis in the U.S.

To ensure its new revenue stream continued, the food industry had some tricks up its sleeve.

For instance, they funded research that downplayed the negative health impact of sugar and suppressed their own research that linked sugar to heart disease. They also made sure to highlight and reiterate health concerns around fat.

Low-fat foods today

Science has moved on since the 1980s, and the all-fat-is-bad theory did not stand up to scrutiny. 

In a recent ZOE podcast, ZOE’s chief scientist Sarah Berry explained that there is no good evidence that — compared with moderate-fat diets — low-fat diets reduce obesity or the risk of type 2 diabetes or heart disease.

Indeed, eating “good” fats, such as those in nuts or oily fish, for example, might reduce the risk of heart disease.

Although nutrition science has shifted focus, food manufacturers are happy to continue pushing these foods, which still contain more sugar than their “regular” versions.

There is also evidence that the food industry still tries to underplay the harmful effects of excess sugar consumption.

And because shoppers are inundated with low-fat products featuring smiling, slender people on their labels, many still think they’re the healthier option.

However, to remove fat from food that naturally contains fat — such as milk or yogurt — it must be processed. This processing removes beneficial nutrients and adds unnecessary and potentially unhealthy compounds. 

For instance, manufacturers may need to add starches, emulsifiers, flavorings, stabilizers, and preservatives to help replace the flavor and texture of fat.

Although you can buy low-fat versions of most types of foods these days, we’ll look at three common examples in a little more detail.

Yogurt

Yogurt, in its natural form, is healthy when eaten in moderation. Yes, many natural yogurts are high in fat, but they are also rich in micronutrients and probiotic bacteria. These bacteria can boost your gut microbiome, which has widespread positive effects on overall health.

Low-fat yogurt, however, is heavily processed and generally includes added sugars. It may also contain flavorings, whey proteins, and pectin. Importantly, processing often removes the friendly, gut-boosting bugs.

If you’d like to know which bacteria currently live in your gut, start by taking our free quiz today. Based on your unique biology, we can provide you with detailed, personalized nutrition advice to help you boost your “good” gut microbes.

Removing fat also removes fat-soluble vitamins, such as vitamins A, D, E, and K. 

Some manufacturers will then add these vitamins back into their products. This gives them an opportunity to announce the “added vitamins” on the label to enhance the product’s “healthy” image, despite them simply replacing what their processing removed.

Milk

Skim milk is widely considered healthier than whole milk. However, the truth is not so straightforward. 

As we saw with yogurt, removing the fat also removes some fat-soluble vitamins. It also removes healthy omega-3s, which are present in milk from grass-fed cows. Again, some manufacturers may add these vitamins back into their products. 

The processing of skim milk also produces a product with slightly more natural sugars than whole milk

For many years, scientists thought that skim milk might help reduce cardiovascular risk. However, more recent evidence suggests that whole milk might protect against heart disease and type 2 diabetes.

People who are trying to lose weight often choose skim milk. However, as ZOE’s scientific co-founder Prof. Tim Spector explains in his upcoming book, Food For Life:

“Contrary to [USDA] advice to choose reduced-fat dairy, low-fat milk has no advantages over whole milk for weight control. In children, the evidence actually suggests greater long-term weight gain with reduced-fat milk than with full-fat milk.”

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Breakfast cereals

Breakfast cereals commonly claim to be low in fat and fortified with vitamins and minerals. 

As you might have already guessed, many of these cereals are high in sugar. Some also have high levels of salt. So, it’s best to check the labels before you buy. 

Even some of the healthiest looking cereals, such as low-fat granola, contain 22 g — more than 2 tablespoons — of sugar per 100 g (1 cup).

And, as we saw with milk and yogurt, the industrial processing of the natural product, in this case often grain, removes much of the nutrients. To make the product seem healthy, manufacturers then add nutrients back in, boldly announcing “added vitamins” on the pack.

If you’re checking the ingredients list for added sugars, there are a couple of things to keep in mind:

Firstly, packages often display the sugar content per serving — it’s worth sense-checking that figure. Sometimes, manufacturers will use an unrealistically small suggested serving size to make the sugar content seem more reasonable. 

Secondly, food manufacturers sometimes hide sugar within ingredients or behind different names. Look out for these hidden sources of carbohydrate:

  • high fructose corn syrup

  • agave nectar or syrup

  • blackstrap molasses

  • buttered syrup

  • cane juice crystals

  • carob syrup

  • fruit juice concentrate

  • rapadura

  • sorghum syrup

  • sucanat

  • barley malt

  • dextrin

  • dextrose

  • maltodextrin

  • maltose

  • D-ribose

  • galactose

So, what should you do?

At ZOE, we know that the best approach to health is to eat a varied diet rich in plant-based foods and to have processed foods and ultra-processed foods only occasionally.

If you are consuming fats in their original form — for example, as part of a whole nut or in full-fat natural yogurt — as long as they are consumed in moderation, for most people, they are healthy.

If the last century was the century of low-fat diets, the coming century will be the century of personalization.

ZOE’s scientists have shown that everyone responds differently to foods. When you eat, you will experience a rise in blood sugar and, a little later, your blood fats will be elevated.

This is normal, but if these shifts in sugar and fat persist or are more extreme, it can cause health problems over the longer term.

Even identical twins have different blood sugar and blood fat responses to the same food. ZOE’s research shows that how you respond to the fats in your diet is unique to you.

By taking ZOE’s at-home test, you can understand how your body responds to food. From that information, we can provide you tailored nutrition advice, including how much fat is good for your body, and the best sources of fat for you.

We’ll also analyze your gut microbiome and recommend the best foods to boost your “good” bugs.

Nutrition is complex, but by understanding your body, you can start eating the right foods for you.

Sources

A systematic comparison of sugar content in low-fat vs regular versions of food. Nutrition and Diabetes. (2016). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4742721/ 

Do Sugar-Sweetened Beverages Cause Obesity and Diabetes? Industry and the Manufacture of Scientific Controversy. Annals of Internal Medicine. (2016). https://www.acpjournals.org/doi/10.7326/L16-0534 

Effects of full-fat and fermented dairy products on cardiometabolic disease: Food is more than the sum of its parts. Advances in Nutrition. (2019). https://pubmed.ncbi.nlm.nih.gov/31518411/ 

FoodData Central. (n.d.). https://fdc.nal.usda.gov/index.html 

How the ideology of low fat conquered America. Journal of the History of Medicine and Allied Sciences. (2008). https://academic.oup.com/jhmas/article/63/2/139/772615

Obesity as an independent risk factor for cardiovascular disease: a 26-year follow-up of participants in the Framingham Heart Study. Circulation. (1983). https://pubmed.ncbi.nlm.nih.gov/6219830/ 

Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. The New England Journal of Medicine. (2018). https://www.nejm.org/doi/full/10.1056/nejmoa1800389 

Sugar industry and coronary heart disease research. JAMA Internal Medicine. (2016). https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2548255 

Sugar industry sponsorship of germ-free rodent studies linking sucrose to hyperlipidemia and cancer: An historical analysis of internal documents. PLOS Medicine. (2017). https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2003460