The low fat diet - weight loss myth or justified?

Low fat diet - an efficient method to lose weight quickly and specifically or the starting signal for a nutrient deficiency and further negative consequences? Eating low fat was strongly propagated some time ago as a way to lose weight and prevent cardiovascular diseases. In the meantime, however, science is relatively unanimous that a radical fat-free diet in particular is detrimental to health and can have many negative consequences in the long term. However, there are less extreme forms of the low-fat diet that can be justified, at least in phases.

 

What is the Low Fat Diet?

There are different variations of this diet. Basically, it is based on the principle that a low-fat diet automatically results in fewer calories being consumed. This assumption is based on the fact that fat is the macronutrient with the highest energy density: 1g of fat has 9.3 kilocalories - carbohydrates and protein have only 4.1 kilocalories per gram in comparison.

In addition, low fat diet fans assume that fat makes you fat, because the equation sounds logical: fat = body fat. Since too much body fat can lead to fatty tissue and arteries on the one hand, which causes long-term health damage, and many people want to look slim, it sounds plausible to simply eat less fat for this reason. Well, both of these reasons for eating less fat are understandable - however, the human organism and its metabolism are quite complex, which is why there are other dietary adjustments that are much more efficient.
The low-fat diet can have many disadvantages, especially in terms of health: Hormonal imbalances, a lack of essential fatty acids, which the body needs for the stability of cell walls, the brain and many other mechanisms, and the reduced intake of fat-loving vitamins and minerals are just some of them. In addition, much more sugar is often consumed instead of fats, which then again has indirect negative consequences for health, body fat reduction and general well-being.

 

Low Fat Diet Explanation - How the Trend Started - A Historical Excursion into the Diet World

The hype of the low fat diet started in the 90s of the 20th Century and continued through the years until today - although not as popular as back then. At that time, due to rapid world development and the industrialisation of food through the new abundance of food, cardiovascular diseases and obesity came into the sights of doctors, nutrition experts and private individuals. Especially in the USA and the beauty and slimming craze in Hollywood, where a new diet craze was constantly hyped, low fat diets became more and more popular. The trend then also quickly arrived in Europe and Germany.

 

How many grams of fat can you eat on the Low Fat Diet? The Low Fat Diet Macro Distribution

There are different definitions within the low fat diet rules of how many grams of fat should be eaten per day. For the most part, the recommendations are based on the basic calorie requirement and are described accordingly in percentage terms: Depending on how radical the approach is, 10-30 % of the daily calorie intake may come from fats. With the 30 %, one would actually already be at the daily amount recommended by the German Nutrition Society1. However, it should be noted that a large part of the population is less compliant with these guidelines and for many the 30 % already means a reduction in fats. For an average woman with a daily requirement of 1600 kilocalories per day, this would mean 50-60g of fat. However, the low fat diet often aims for a much lower dietary fat target:

In the 30-gram fat diet, no more than the 30 grams of fat mentioned above may be consumed per day. If you orientate yourself on the lower limit, the 10 % of the daily calories, you will then be at just 15 to 20 g of fat per day. How much fat is actually consumed per day on this diet is also a matter of interpretation. As you can see, there are very radical forms and milder ones that are based on official health recommendations.

To get down to as few grams of fat per day as possible, dishes are prepared with little fat: Lean meats are boiled instead of fried, low-fat yoghurts are consumed and high-fat foods such as butter, pure oils, nuts and cream are avoided. Instead, the low-fat diet plan includes things like reduced-fat margarine, often industrially processed low-fat and light products, more carbohydrates and fruit and vegetables. This is part of the problem with the low-fat diet: most people think in black and white terms and avoid only the macronutrient fat. Too little attention is paid to the quality of food and sugar in low-fat products.

 

Low Fat Diet: pros and cons

If you don't do the low fat diet too radically and stick to at least 30 to 40g of fat daily, it can actually lead you to faster weight loss in a short time. These are sometimes unavoidable for competitive athletes when they need to reach the right weight for their weight class before a competition or a bodybuilder who wants to reduce his body fat to a minimum. It can also be beneficial for an intestinal rehabilitation to minimise dietary fats very much from time to time. In the carb cycling diet, which is popular with bodybuilders and in the fitness world for aesthetic goals, alternate between high fat and high carb days. This can also be beneficial for the metabolism, and since regular high-fat days occur, the risk of deficiencies in essential fatty acids and prevented absorption of fat-soluble vitamins is low.

If the benefits are to be truly sustainable, however, this low-fat diet should never be followed radically over the long term, i.e. no more than one to two weeks at a time with the maximum 15g to 20g of fat daily. In addition, care must still be taken to consume little sugar and not to resort to industrially processed low-fat foods. Otherwise, the low fat diet is not advisable, because it carries some risks and is often much less effective than the low carb diet...

 

Low fat or low-carb diet - which is more efficient?

The Low Carb Diet has already been described in more detail in the article on the "ketogenic diet". In this diet, a lot of fats and a maximum of 30-40g of carbohydrates are consumed daily - the opposite of the low fat diet. Since carbohydrates are not essential for the body - it can produce them, or a substitute, itself from other substances if they are not supplied through food. This is different with fats: there are numerous essential fatty acids that the body cannot synthesise itself and that must necessarily be ingested through food. Omega-3 fatty acids, for example, are among these essential fats. In addition, the intestinal mucosa needs the right fats to maintain its protective layer. All other cell membranes also consist of a lipid layer.

Fats are also the basis for all steroid hormones, making DHEA, testosterone, oestrogen, cortisol, and vitamin D3 dependent on the macronutrient. The hormone cascade can be severely compromised on a long-term low fat diet, which can have many negative consequences - both physical and mental. A radical low fat diet is also bound to result in vitamin deficiencies: Vitamins A, K and D are fat-soluble and cannot be absorbed without fats. More on the topic of fats can be read in the article "Why fat is not equal to body fat".

 

Conclusion on the low fat diet

A long-term low-fat diet can have dangerous health consequences and is also much more inefficient for body fat reduction goals than other diets. However, the low fat diet as an interval solution, i.e. with a low fat week or alternating low and high fat days, can give the metabolism new positive stimuli. In addition, it makes sense to reduce industrially processed fats and trans fats and to use natural fats and native oils instead.

 

References:
1 DGE: Referenzwerte Fett. [https://www.dge.de/wissenschaft/referenzwerte/fett/?L=0; 18.02.2021].

 

Häufig gestellte Fragen

What is the Low Fat Diet?
There are different variations of this diet. Basically, it is based on the principle that a low-fat diet automatically results in fewer calories being consumed, which leads to weight loss. The hype of the low-fat diet started in the 90s and has continued over the years until today - although not as popular as back then. At that time, cardiovascular diseases and obesity came into the focus of doctors, nutrition experts and individuals due to the rapid world development and the industrialization of food through the new abundance of food.
Low carb or low fat - which is better and more efficient in the long run?
Definitely low carb. Since carbohydrates are not essential for the body - it can synthesise them, or a substitute, itself from other substances if they are not supplied via food. With fats it is different: there are numerous essential fatty acids that the body cannot synthesise itself and that must necessarily be taken in via food. Omega-3 fatty acids, for example, are among these essential fats. In addition, the intestinal mucosa needs the right fats to maintain its protective layer. All other cell membranes also consist of a lipid layer. Fats are also the basis for all steroid hormones, which means DHEA, testosterone, oestrogen, cortisol, vitamin D3 and are dependent on the macronutrient. The hormone cascade can be severely compromised on a long-term low fat diet, which can have many negative consequences - both physical and mental. A radical low fat diet is also bound to result in vitamin deficiencies: Vitamins A, K and D are fat-soluble and cannot be absorbed without fats.
High Carb, Low Fat - what can I (not) eat?
In the extreme low fat high carb diet form, there is the so-called 30 gram fat diet, where no more than the mentioned 30g of fat per day may be consumed. Another version of this prescribes that only 10% of daily calories may be fats. Lean meats are boiled instead of fried, low-fat yoghurts are consumed and high-fat foods such as butter, pure oils, nuts and cream are avoided. Instead, the low-fat diet plan includes things like reduced-fat margarine, often industrially processed low-fat and light products, more carbohydrates and fruit and vegetables.
What is low-carb, high fat for an approach to ketogenic processes?
If no carbohydrates are consumed through food, after a while the body begins to deplete the carbohydrate stores from the liver and use them as an energy source for nerve cells and the brain, for example. The glycogen stores in the muscles are then also slowly emptied. However, since these sugar stores are depleted without their new intake through food, the liver first begins to convert amino acids (the broken-down form of proteins) into carbohydrates. In the ketosis that now occurs, the liver converts the fats into so-called ketone bodies. Although they cannot be transformed into the sugar that is actually needed, they fulfil the same functions in energy metabolism. They are therefore more or less a substitute for carbohydrates.
How does the Low Fat 30 Diet work?
In the extreme low fat high carb diet form, there is the so-called 30 gram fat diet, where no more than the mentioned 30g of fat per day may be consumed.
How much fat is allowed per kilogram of body weight for low fat?
There are different definitions within the low fat diet rules. The recommendations are often calculated as a percentage: Depending on how radically the matter is approached, 10-30 % of the daily calorie intake may come from fats. The 30 % would actually already be the daily amount recommended by the German Nutrition Society. There is the 30 gram fat diet, in which no more than the 30g of fat mentioned may be consumed per day. If you orientate yourself on the lower limit, the 10 % of daily calories, you are then at just 15-20 g of fat per day.
What is the best amount of fat to consume on the Low Carb, High Fat Diet?
Bei der Low Carb High Fat (auch Keto Diät) sollten pro Tag nicht mehr als 30-40g Netto Kohlenhydrate konsumiert werden. Diese ergeben sich primär aus Gemüse oder Beeren. Dafür soll ausreichend Protein zu sich genommen werde und Fett dient als Hauptenergiequelle. So werden 75-85 % der täglichen Kalorienmenge aus Fettsäuren bezogen.
In the low carb high fat (also keto) diet, no more than 30-40g net carbohydrates should be consumed per day. These come primarily from vegetables or berries. In return, sufficient protein should be consumed and fat serves as the main source of energy. Thus, 75-85% of the daily calorie intake is derived from fatty acids.

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