5 Outdated Nutrition Trends We Cringe At Now & Why They Never Worked

I remember the first time I realized that food wasn't immune to trends. I was visiting a friend at the age of 10 or 11, and we were standing in her kitchen, dripping wet in our towels after swimming for hours. We were eating string cheese when her mom remarked that our snack looked delicious, but she couldn’t have any because she was “not eating fat right now.”

Her kitchen bookshelf wasn’t stocked with cookbooks, but dieting books—low-fat this, low-carb that, zero-sugar everything, and one that stands out in my memory: The grapefruit diet. I was confused, trying to grasp that, like fashion, food trends come and go. The dark side of this realization was that outdated or downright poor nutrition advice didn't get discarded and was circulated through seemingly reputable sources and engrained in our norms.

It wasn't this mom's fault—she was being fed misinformation with false promises from people who, at the time, seemed like credible sources. And there seemed like no reason not to follow their advice.

Fast forward 15 years, and here we are—in a time where protein is leading the charge and cutting out entire food groups feels like an ancient concept. We’re now celebrating strength, confidence, and body empowerment rather than shaming anyone who isn’t a size 0.

That said, we still have a long way to go. And to be fair, we might look back at today’s nutrition advice as outdated and absurd one day. But overall, I’d wager that we’re doing better now than we were back then.

First, let’s dive into one that hits close to home for so many: the low-fat craze.

How it started

“During the 1980s, low-fat diets became the go-to solution for high cholesterol, weight gain, and cardiovascular disease,” says Maya Feller, R.D. With rising cholesterol levels across the U.S. and a growing obsession with weight loss, low-fat diets took center stage.

Kim Shapira, M.S., R.D., echoes this, noting, “This trend was big in the ’90s, often called the ‘snackwell era.’ As obesity rates climbed, Americans were told that reducing fat intake might lower the risk of cardiovascular disease and obesity.”

The low-fat movement gained momentum from two main sources: advice from physicians and shifts in the food industry. “Instead of focusing on low-fat suggestions, U.S. physicians began recommending low-fat diets for all Americans, not just those with metabolic dysfunction,” Feller explains.

She adds, “Along with these recommendations, food manufacturers started creating low-fat versions of baked goods, chips, cookies, and more. To compensate for the lost ‘mouthfeel’ when fat was removed, many of these products were loaded with added sugar and fillers.” Does anyone else remember those zero-fat brownies, or is it just me?

Some products even included Olestra, a fat substitute that caused fat malabsorption. Unsurprisingly, this backfired, leading to unpleasant and harmful gastrointestinal symptoms for many consumers, as Feller recounts.

What we know now 

While you can still find low-fat yogurt on grocery store shelves, we’ve largely moved away from demonizing this essential macronutrient. “In recent years, health care providers have recognized that heart-healthy fats are crucial for increasing the bioavailability of fat-soluble vitamins in meals and promoting satiety,” says Feller.

Among the many niche diets, Britta Reierson, M.D., finds the blood type-specific diet particularly lacking in scientific backing.

How it started

This trend began with a naturopathic physician and a book released in the late ‘90s, claiming that people have different nutritional needs based on their blood type. Following this diet was supposed to lead to weight loss, disease prevention, and increased energy, among other steep claims. 

Reierson understands why this diet became so popular. “This fad quickly gained traction because it seemed logical—given the scientific knowledge about blood types and individual differences. For instance, an unmatched blood transfusion can cause severe reactions, so it made sense to think that blood type could dictate the best diet for optimal health and to avoid ‘mismatches’ or intolerances.”

The diet was so specific that it felt more actionable than general healthy eating advice—if you have blood type B, you should avoid chicken and lentils and eat tons of berries. If you have blood type A, you should avoid potatoes and cow’s milk but eat lots of salmon and pineapple. You get the point. 

What we know now

“To date, there is no scientific evidence to support the benefits promoted by the Blood Type Diet,” Reierson asserts.

However, she acknowledges that some people have seen success with this diet—not due to their blood type, but because it significantly reduces processed foods, which are known to harm metabolic health. You’ll find processed sugar on the “no” list for most people, naturally. 

“Regardless of blood type, the Blood Type Diet’s elimination of most unhealthy processed foods is associated with better health markers,” she notes.

There was a time when eggs were in the hot seat, mainly for cholesterol reasons—and thank goodness that’s over. 

How it started

“Because egg yolks contain cholesterol, it was believed that cholesterol in foods raises blood cholesterol levels, so people stopped eating whole eggs if they were at risk,” says Shapiro.

Eggs were seen as a primary cause of high cholesterol, leading many physicians to recommend that everyone treat egg yolks as an occasional indulgence rather than a daily staple.

The food industry supported this view by promoting egg whites as a healthier alternative, further fueling the anti-egg yolk movement.

What we know now

“We now know that cholesterol in foods does not raise blood cholesterol levels,” Shapiro explains, pointing out that saturated fats and simple carbohydrates are the real culprits.

Recent research1 has proven that eggs are a nutritious, affordable food that doesn’t raise cholesterol levels. The yolk, in particular, is packed with essential nutrients like choline and vitamin D. 

Shapiro emphasizes that eggs offer unbeatable nutrition for their price and accessibility. During the anti-egg yolk era, Shapiro remembers many people mixing egg whites with bacon or cheese for more flavor, inadvertently increasing their intake of saturated fats, which did nothing to lower cholesterol.

Now, let’s dive into the grapefruit diet and its cousin, the Special K diet. Buckle up; this one gets a bit strange.

How it started

Reierson vividly remembers both of these weight loss “diets,” if they can even be called that. The Special K Diet became popular in the early 2000s as a quick-fix solution for weight loss. 

“Marketed by Kellogg’s, it promised weight loss with minimal effort by replacing two meals a day with Special K cereal and eating a sensible third meal. Its simplicity and the allure of a branded plan made it appealing,” she says.

Similarly, the grapefruit diet, which began in the 1930s, has been debunked repeatedly. “It claimed that eating grapefruit with every meal would boost weight loss due to its fat-burning enzymes,” Reierson explains. 

The diet recommended eating at least half a grapefruit with breakfast, lunch, and dinner, suggesting that one could lose 10 pounds in 10–12 days. The high water content in grapefruit might have kept some people feeling full, but the real factor behind the weight loss was the severe caloric restriction, often down to 800 calories a day.

What we know now

Reliance on a single food, whether it’s a branded item or something like grapefruit, leads to nutritional deficiencies and severe caloric deficits. “Research shows that long-term weight management is best achieved through diverse, balanced eating habits rather than short-term, monotonous diets,” says Reierson. While cereals and grapefruits offer benefits and nutrients, “they shouldn’t be the foundation of your diet,” she adds.

She points out that chronic calorie restriction can lead to hormonal imbalances and a loss of essential lean body mass (like muscle and bone), which in turn lowers your metabolic rate and increases the likelihood of regaining lost weight.

What we know now

According to Knudsen, fat loss is a complex issue that goes beyond mere calorie counting and eating as little as possible. 

“Eating more protein, increasing your fiber intake, focusing on building muscle, and improving your sleep and stress management are all crucial for a successful, long-term relationship with food and body recomposition.” Because the goal is body recomposition (aka changing the ratio of fat to muscle mass in your body), not watching the number of the scale go down and taking your muscle mass with it.

Whether it's low-fat everything, bizarre food obsessions, or the demonization of healthy foods, we've seen a lot of misguided nutrition advice over the years. What do these have in common? They're all focused on restriction, limiting food intake, and fear. The good news is that we're in a better place now than we once we're. We now know what works in the nutrition realm is none of the above—it's all about diversity on your plate, balance, and consistency of daily habits.

This isn't to say we're free from seeing poor nutrition advice on social media—there's still plenty to go around–but it's getting better, and there's more credentialed experts taking to the internet to debunk new myths and spread science-backed tips that actually help us lead healthier, happier lives.