Should we still be following a low-fat diet or is it making us fatter?
Supplements | By Emerson Ecologics | Jul 1, 2020
Over the past few decades, Americans have been getting heavier and heavier. In the late 1970s, the obesity rate (determined by having a Body Mass Index or BMI of 30 or more) in adults was only about 15%. By 2008, it was 34%. During the same time period, obesity among children rose from 5% to 17%.
As a result, we’ve seen a variety of diet programs spike in popularity, including the low-fat diet, low-carb diets like Atkins and the South Beach Diet, the keto diet, the Mediterranean diet, and countless others. For a while in the 1980s and ‘90s, the low-fat diet was the most recommended, but these days, we’re seeing more high-fat diets come into fashion.
What happened to the low-fat diet? Is it still considered healthy? Did it help people lose weight? And should we go back to it?
Let’s dig into that data and hear from some experts to answer those questions.
The Emergence of the Low-Fat Diet
In the 1990s, the low-fat diet became the norm. Fat was demonized in medical communities and the media, thanks in part to reports released in the 1980s claiming that people (not just Americans) needed to reduce their fat intake or avoid it altogether. This stemmed from research showing that dietary fat was related to cardiac disease — a consensus that has been largely upheld, with some caveats.
As a result of this push to reduce dietary fat intake, low-fat snacks and baked goods filled the grocery store shelves. Author and chair of New York University’s Department of Nutrition, Food Studies, and Public Health, Marion Nestle calls this ‘the Snackwell Phenomenon.’ “Snackwell cookies were advertised as no-fat cookies, but they had almost the same number of calories,” Nestle says.
But because people were being told to eat a diet low in fat, they started believing that low-fat foods were “healthier,” regardless of what was on the ingredient label. In fact, many consumers didn’t even read the ingredient label at all, assuming that because the package said it was low-fat, it must be good for them.
Today, perceptions have shifted, and we have a multitude of diet examples to prove it. We have very high-fat, low-carb diets, such as the keto diet and the Atkins diet, we have more moderate approaches like the South Beach diet and the Mediterranean diet, and others that promote consuming less animal products to focus on plant-based ingredients, such as vegetarian and vegan diets.
While a low-fat diet is still generally agreed upon in the medical community as the best meal plan for people at risk of heart disease, we understand more about how fat interacts with the body, and which fats are healthy for you.
Is Fat Bad for You?
One of the perceptions that came out of the low-fat diet push — and that has been difficult to unseat — was that all fat was bad for us, or that eating fat would make us fat. Not all fats are created equal — there are good fats and bad fats and in-between fats, just like there are good carbs and bad carbs.
Trans fats are the types of fat that should be avoided. While there may be very small amounts of naturally occurring trans fats in animal and dairy products, artificial trans fats are absolutely not up for debate.
Artificial trans fats are so dangerous that in 2003, the FDA actually amended their food labeling regulations to require that trans fatty acids be listed in nutrition labeling so that people could steer clear of them. While these are sometimes listed as “trans fats” on ingredient labels, very small amounts can also be “hidden” through terms like hydrogenated oil, or partially hydrogenated oil. There are no known health benefits to trans fats.
There is one bit of good news on the bad fat front: the FDA has instructed all partially hydrogenated oils to be removed from food by January 1, 2021.
Fats for Moderate Consumption
Saturated fats are found in most foods of animal origin including beef, pork, poultry and dairy products. While not healthy in large amounts, they are fine in small amounts as part of a balanced diet. Because environmental toxins accumulate more in the fat of animals than their meat, it’s best to buy organic animal products if possible. Some practitioners, such as Dr. Mark Hyman, MD and Dr. Josh Axe, DC, DNM, CNS, recommend choosing organic butter and grass fed or pastured meats and poultry.
Monounsaturated fats have one double bond in their fatty acid chain, with the rest being single-bonded carbon atoms, and includes Omega-9 fatty acids. “Monounsaturated fats specifically, are known to promote heart health by decreasing LDL cholesterol levels, thus reducing risk of heart disease and stroke,” says Claire Carlton, MS, RD. “You can incorporate more monounsaturated fats by cooking with olive oil, snacking on nuts or adding avocado to a sandwich in place of mayonnaise.”
Polyunsaturated fats have more than one double bonded carbon atoms in their fatty acid chain. Omega-3 and 6 fatty acids are polyunsaturated fats. “Omega-3 fatty acids are another essential fat to prioritize,” says Carlton. “With their anti-inflammatory properties, omega-3 fats help to balance out intake of pro-inflammatory omega-6 fats, which are abundant in the standard American diet.”
Additionally, the human body cannot make omega-3 fatty acids, which is why they’re called “essential” fatty acids — we must get them from our diets or supplements. Carlton recommends adding salmon, walnuts and flaxseeds to meet those dietary needs.
Did the Low-Fat Diet Make People Fatter?
In theory, a low-fat diet should make people lose weight because fats have lots of calories, and if you reduce the amount of fat in food, that means fewer calories. But it’s really not that simple, because this assumption is based on the fact that people won’t change any other aspect of their eating habits.
In reality, a large portion of the problem with the obesity epidemic in America has to do with our portions. As Tufts University Friedman School of Nutrition Professor Jeanne Goldberg told Frontline, “I think a lot of this issue begs the question of a concept that Americans have a really hard time with. It's that concept of moderation. If we could eat two cookies and move on, we'd need a lot less of what I call this jiggering with the food supply. But we don't. We want to eat a lot of things, and a lot of what we eat, and a lot of variety.”
Nestle also attributes the obesity epidemic to another overlooked aspect of the low-fat push: calories. “There was a huge educational campaign to try to get people to eat less saturated fat, and that encouraged Americans to choose low-fat milk over whole milk — that's been a big shift — and to use vegetable oils instead of animal fats,” which she says isn’t necessarily a bad thing. Olive oil is unequivocally healthier than butter.
“What didn't accompany that message was a calorie message,” Nestle continues. “Somehow calories got lost in all of that, and the individual nutrients or the individual components were taken out of their caloric context.”
By cutting out the fat, food manufacturers and home cooks alike were making their food taste bland and boring. “When you remove fat you remove flavor, so they need to add something to put the flavor back,” says Erin McNamara, RDN LDN, CLT. And where did that flavor come from?
“When fat was removed from foods, calories came in from sugars, and that didn't help the calorie situation very much,” says Nestle. And of course, that led to another problem that we often overlook: the addictive properties of sugar. “Our taste buds get used to the sweet taste, which makes us want more,” says McNamara.
So while “low-fat diets” don’t inherently make people fatter, the additives that are used to make low-fat foods taste better can easily contribute to weight gain. Furthermore, McNamara says that “people tend to overeat an item if it is low-fat or fat-free because they never feel really satisfied or full. Fat provides both taste and satiety.” And without that signal from the body telling you that you’ve had enough, you’re likely to keep eating.
“Without adequate fat, I see patients complain that their meals don’t keep them full for very long,” says Carlton. “Compare a salad of mixed greens, cucumbers, tomatoes, grilled chicken and fat-free salad dressing to one containing those same ingredients plus toasted pumpkin seeds, a sprinkle of feta cheese and a balsamic vinaigrette made with olive oil. The salad with a healthy dose of fat is going to taste better and keep you energized for longer.”
The bottom line is that a cookie is still a cookie, even when it’s low in fat. Some types of gummy candies are low in fat, but it doesn’t mean they’re good for you. When adhering to a low-fat diet, one must also consider the ways in which they’re making up for less flavor carried by the lipids. Rather than substituting with sugar, be sure to add herbs and spices, which will help you feel more satisfied.
Is a Low-Fat Diet Healthy?
A low-fat diet can certainly be healthy, and is still recommended to most people at higher risk of heart disease, or who need to be on a “heart healthy” diet. On the other hand, a food label that says “low fat” does not always mean “healthy.”
Eating whole foods that are naturally low in fat is not quite the same as basing a diet off of prepackaged foods. Choosing to cook with nonstick spray instead of butter is one thing. Choosing to eat a box of low-fat gummy candies instead of an apple is another. And that’s where the trouble lies with low-fat diets: there are many pitfalls that are quite easy to step into.
Where this type of diet can veer off-course is when people start subbing in more carbohydrates, or eating double the amount they normally would to make up for the low-fat aspect of their diet. A healthy diet needs to have some fat and ample protein in addition to carbs.
“I do not recommend low-fat diets to my clients,” says Claudia Hleap RD, LDN, who works primarily with older adults looking to manage diabetes and weight. “Most research into this debate demonstrates that low-carbohydrate diets are more effective for achieving weight loss than low-fat diets.” Despite the reduced calorie content of some low-fat options, one may end up consuming more calories in the long run due to the lack of fullness provided from the low-fat food,” Hleap says.
Focus on Diets that Stick
Much like any other diet, the main consideration is what an individual can maintain over a long period of time. If a person doesn’t like the taste of some foods included in a diet, they’re not going to stick to it. If they don’t feel satiated while eating those foods, they’re going to venture outside the limits, or eat far too much in an attempt to feel satisfied.
In fact, McNamara actually encourages her clients to choose full-fat products. “Yes, fat is higher in calories than carbs or protein, so portions can add up if you’re not careful. But you will 1) enjoy the taste of foods more, 2) get fuller faster because it is satiating, 3) feel fuller longer because it’s digested slower, and 4) may result in weight loss because you might be eating less.”
The healthiest diet is one that is balanced, varied, and includes lots of whole, natural, unprocessed foods. In fact, many medical professionals say that the Mediterranean diet is the best plan to follow because it embodies all of these principles, includes many anti-inflammatory foods and nutrients, and is even considered to be heart healthy. The best part is that foods included in this diet taste delicious and will keep you feeling fuller, longer.
If an individual needs to keep their dietary fat to a minimum because of medical conditions or history, the Mediterranean diet can fit into that category as well — it’s just a matter of tracking the macronutrients and subbing in more vegetables and fruits if they’ve hit their fat intake for the day.
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