Forty years of low-fat diets: a ‘failed experiment’ - is the title of a 2016 article published by Harvard School of Public Health researchers. Doctors recognize that low-fat diets are still embedded in people’s consciousness and food policies even though research studies tell us that low-fat, high-carbohydrate diets used by Americans for 40 years - are not a good idea.
There are several reasons why low-food foods are not the best choice. It is also important to understand the difference between healthy fats vs. unhealthy fats.
Low-fat diets aren’t that effective diets to lose weight
Many health advocates have recommended low-fat diets, which rely on low-fat, processed foods to lose excess weight. This theory is still around. Yet, a large review of 53 studies involving over 68,000 participants did not find low-fat diets as effective as previously thought. Those who followed a low-carb diet lost more weight than those on low-fat diets. The study also concluded that low-fat diets lead to weight loss only when compared with a usual diet when the participants of the study did not change their diet.
Most low-fat foods are unhealthy
Let’s leave aside vegetables, legumes, and fruits, naturally low-fat foods, and healthy dietary choices.
Low-fat diets contain many manufactured low-fat foods. They are unhealthy because they are highly processed and contain high amounts of carbohydrates and additives. Common unhealthy, low-fat foods include low-fat sweetened cereals and bars (which have added sugars, colors, and preservatives), low-fat flavored coffee, and tea(which may contain over 500 calories and 50 grams of sugar). Low-fat yogurts and low-fat cottage cheese are highly processed and contain added sugar. Natural peanut butter typically contains peanuts and salt, while reduced fat peanut butter contains sugar, corn syrup, and several additives to make it more tasty and smooth.
The many health benefits of fats
Reducing fat intake may have many negative impacts on your health. Fats, carbohydrates, and proteins are classified as macronutrients. Along with essential micronutrients like vitamins and minerals, macronutrients are essential for your health and should be included in a healthy diet. The health benefits of fats include:
- Fats are an important source of energy, and also a source of essential fatty acids that the body can't make.
- All cells in the body need this macronutrient as fat is a key component of the cell walls.
- Fats help absorb vitamins like A, D, E, and K.
- Fats insulate the body and protect the organs.
- Fats help the body produce and regulate hormones. For example, fatty tissue secrets leptin, the hormone that regulates appetite.
- Fats are needed for reproductive health.
- Essential fatty acids regulate cholesterol levels, blood clotting, and inflammation.
- Fats are involved in brain health and nerve impulse transmission.
- Fats add flavor to the food and therefore satisfy the appetite.
Healthy fats versus unhealthy fats (huge difference!)
All fats were labeled “bad” in the past because their consumption was linked with heart diseases, weight gain, high cholesterol, and other metabolic changes. Yet, current research shows a huge difference between different types of fats.
Unsaturated fats include mono and polyunsaturated fats. They are liquid at room temperature. Monounsaturated fats come from natural sources such as nuts, avocado, olives, and olive oil. Polyunsaturated fats are in safflower, sunflower oils, corn oil, and nuts. Olive oil may be healthier than seed oils, which contain fats that promote inflammation. Omega 3 is a special polyunsaturated fat in fatty fish, flaxseed, chia seeds, and walnuts.
For a healthy diet, choose olives, olive oil, nuts, seeds, and fatty fish as the main source of fats. Think about the Mediterranean diet, which contains all these fatty foods and is considered one of the healthiest.
Saturated fats are easily recognized because they are solid or waxy at room temperature. Most of them come from animal sources like beef, lamb, poultry skin, dairy products, butter, lard, and bacon fat. Tropical oils like coconut oil and palm oil are also a source of saturated fats. Most processed foods like hot dogs, bologna, salami, cookies, and pastries contain unhealthy, high amounts of saturated fat.
Saturated diets have a bad reputation because they have been linked with increased risk of cholesterol levels, heart diseases, and fatty liver. However, not all saturated fats are bad, but mostly the ones found in highly processed foods and deli meats. It is best to eliminate from your diet unhealthy saturated fats that are found in processed meats and bakery products, like cookies, croissants, and cakes. Red meat from grass-fed animals and butter can be consumed in limited amounts. Plant sources of saturated fats like coconut and palm oil can also be part of a healthy diet.
Trans fats are formed when liquid fats change into solid fats through hydrogenation and are all considered unhealthy. Many processed foods contain hydrogenated oils because they help increase the shelf life and consistency of foods. There are many health risks associated with trans fats, including an increase in LDL (bad) cholesterol, decrease in HDL (good) cholesterol which further increases the risk of heart diseases, stroke, diabetes, and excess weight. There is no safe “daily amount” of trans fats.
Even “free trans-fat” products may contain trans fats; therefore, it is best to avoid all products that list partially hydrogenated oils as an ingredient on the label. Solid margarine, shortening, processed foods, baking products, and powdered coffee creams are all common sources of partially hydrogenated oils.
Cholesterol. Only animal-based foods contain cholesterol. Eggs, red meat, seafood, and cheese all contain cholesterol. Avoid excess cholesterol, especially if you have high blood cholesterol levels.
Based on current recommendations, about 30% of caloric intake should come from fats, and most fats (70%) consumed should be unsaturated. Saturated fats should be limited to less than 10% of total fats consumed and 0% trans fats. Focus on healthy fats and stay away from trans fats.
If you have cholesterol levels within the normal range, limit the intake to no more than 300 mg a day. If you have high cholesterol, limit the daily intake to less than 200 mg.
Use the Mediterranean diet to guide a healthy diet containing moderate amounts. High and very high-fat diets like ketogenic diets also show many health benefits in research studies. It is best to work with a healthcare professional when choosing a diet that significantly increases or limits certain nutrients.
Enjoy more homemade meals and eliminate processed foods.
Consider the carbohydrate and protein intake and how to add more plant-based foods to the diet. Vegetables, fruits, legumes, herbs, and spices are also part of a healthy diet, as great sources of vitamins, minerals, fibers, and other beneficial plant compounds.
- Harvard T.H. Chan School of Public Health. Forty years of low-fat diets: a failed experiment.
- Harvard T.H. Chan School of Public Health. Low-fat diet not most effective in long-term weight loss.
- NIH. Ketogenic Diet and Weight Loss: Is There an Effect on Energy Expenditure?
- Cleveland Clinic. Do Fats Make You Fat?
- Open Oregon Educational Resources. The Functions of Fats.