Light Products — What Happened When the Fat Disappeared?

Open an American refrigerator sometime in the 1990s and you'd find them right away: the skim milk, the fat-free yogurt, the tub of margarine. They weren't there by accident. They were there because they were the responsible choice — what you bought when you cared about your health and your family.

A light product is, simply put, a food in which a nutrient — usually fat, sometimes sugar — has been reduced compared to the original product. Today the term is regulated: in the US, the FDA allows a product to be labeled "light" or "lite" if it contains at least one-third fewer calories or at least 50 percent less fat than the reference food.

But to understand why the shelves filled up with them, we need to go back to the 1980s. Fat — especially saturated fat — had been singled out as a central risk factor for cardiovascular disease, and dietary advice around the world urged people to eat lower-fat foods. The logic was straightforward and, given the knowledge of the time, entirely reasonable: if fat was the problem, less fat should be the solution. The food industry responded to the demand, and "light" became, in practice, synonymous with "healthy."

It's worth saying clearly: anyone who chose light products did nothing wrong. It was the best guess of the era, translated into everyday choices. The question this article asks is what happened next — in the products and in the research.

Fat in food does more than provide energy. It carries flavor and aroma, gives creaminess and texture, and contributes to feelings of fullness. When fat is removed from a product, it's not just calories that disappear — it's the qualities that make food enjoyable and satisfying to eat.

That created a practical problem for anyone trying to manufacture a low-fat cookie, yogurt, or sauce: something had to replace what the fat used to do. In many products, the answer became sugar, refined starch, thickeners, and other additives. The nutrition label showed less fat — but the whole product had changed in more ways than that.

Hidden here is a question that turned out to be central, and that was long overlooked in both research and dietary advice: instead of what? The effect of removing a nutrient depends on what fills the void. Swapping saturated fat for vegetables and whole grains is one thing. Swapping it for sugar and white flour is another. During the golden age of light products, "less fat" was often treated as a win in itself — regardless of what came in its place.

There's also a psychological dimension. A food perceived as healthy tends to be eaten with a clear conscience — and sometimes in larger amounts. That mechanism would turn out to play an unexpectedly large role.

The SnackWell's phenomenon: a textbook example

The story even got a name. In the 1990s, SnackWell's was launched — low-fat cookies and crackers that became an enormous sales success. They were marketed as the smart choice, and many people ate them exactly that way: as something you could indulge in without guilt. The problem was that the cookies were still energy-dense, now with more sugar and refined flour in place of fat — and that the clear conscience, for many, meant the portions grew. The "SnackWell's effect" became an established concept in nutrition research: when a food is stamped as healthy, consumption can increase so much that the intended benefit never materializes.

What happened to weight?

Perhaps the most illuminating study for the entire replacement question is Mozaffarian, D. et al. (2011), published in the New England Journal of Medicine. The researchers followed more than 120,000 Americans for up to 20 years and examined how changes in diet were linked to weight change over time. The results did not point to fat as the main culprit. Instead, it was foods like french fries, sugar-sweetened beverages, potato chips, and refined grains that were most strongly associated with weight gain — while vegetables, whole grains, fruit, nuts, and yogurt were linked to weight stability or weight loss. The study is observational and shows associations, not causation, but the pattern is telling: it seemed to matter more what kind of food you ate than how much fat it contained.

The sugar that came instead

At the same time, research grew on what often replaced the fat. Yang, Q. et al. (2014), published in JAMA Internal Medicine, found in a large US population study that a high proportion of added sugar in the diet was associated with an increased risk of dying from cardiovascular disease. Here too, we're talking about associations, not proven cause — but the finding illustrates the irony of the story: fat was reduced partly in the name of heart health, while its replacement was in turn linked to cardiovascular outcomes.

On refined carbohydrates, Ludwig, D. et al. have argued in several works, including on the glycemic index (2002, JAMA), that rapidly digested carbohydrates produce blood sugar swings that may affect hunger and eating behavior. The scientific picture on the exact mechanisms is still debated, but studies consistently suggest that refined carbohydrates in large amounts were not the neutral replacement they were once assumed to be.

From nutrients to dietary patterns

Perhaps the most important shift is visible in how research now frames its questions. Modern guidance — including the Dietary Guidelines for Americans and the Nordic Nutrition Recommendations NNR 2023 (Blomhoff, R. et al., 2023) — puts the emphasis on whole dietary patterns: plenty of vegetables, legumes, whole grains, fish, and nuts, less red meat and added sugar — rather than on individual nutrients in isolation. A "light" label says something about one nutrient in one product. It says nothing about the product as a whole, and even less about the diet as a whole.

Two points that must be kept apart

It's easy to draw the wrong conclusion from this history, so let's be careful. First: some of what happened was, in hindsight, worse than it needed to be. The evidence behind the single-minded focus on fat was incomplete, and when fat was swapped for sugar and refined carbohydrates, the net effect for many people wasn't what they'd hoped for. The right conclusion from that is not that dietary advice is pointless — but that better general advice is needed, built on better data. And that's exactly what has happened: today's recommendations rest on a broader and stronger evidence base.

Second: even genuinely good general advice represents averages, and individuals deviate from averages. But that's a separate question — and never an excuse for the first point. The fact that knowledge was incomplete then doesn't mean "everyone is right in their own way." It means that knowledge can be refined — and that it has been.

The story of light products, in other words, is not a scandal but a chapter — one of several — in the larger story of how dietary advice is reexamined and sharpened as evidence grows. That story, from the 1977 US Dietary Goals to today's recommendations, is one we've written about in Om kostråden ändrats förr — hur vet vi att dagens råd stämmer?.

This article offers no dietary advice — neither for nor against light products. Some reduced-fat products serve a purpose for some people, and for current dietary recommendations we refer you to the Dietary Guidelines for Americans (USDA/HHS). But the story above points toward a few approaches many people find helpful when navigating product claims:

• Read the claim for what it is. "Light," "low-fat," or "less sugar" describes a single nutrient compared to an original product — not the product as a whole. The ingredient list and nutrition facts panel give a fuller picture than the front of the package.
• Ask the replacement question. When something has been taken out of a product, it can be illuminating to look at what came in its place. The history of light products shows that this is often where the interesting part is.
• Watch out for the health halo. The SnackWell's phenomenon is a reminder that foods perceived as healthy are sometimes eaten in larger amounts. Many people find that this insight alone changes how they relate to "virtuous" products.
• Interpret shifting advice as refinement, not chaos. The fact that advice gets updated is a sign that knowledge is growing. Anyone who wants to understand that process in depth can read more in our pillar article on the history of dietary guidelines.

And as always: for questions about your own health or if you have symptoms, healthcare professionals are the right address — not an article.