Adam C. Stewart
There is no doubt that we need dietary fats. However, when it comes to exactly what we need, definitive answers are difficult to find. This short article aims to provide factual information about the minimum fat requirements.
Note: This article was the cover of MASS Research Review for September 2023 and is the first part of a new type of mass article entitled “out of the mailbag.”The goal is to answer questions from mass readers (or frequently asked questions in the evidence-based Fitness community). If you want more content like this, subscribe to MASS.
How many dietary fats do we really need? This is one of the most common questions that overwhelms even the most experienced and experienced fitness professionals from time to time.
Before you start answering this question, it is really important to formulate the question consciously. When it comes to the amount of dietary fat we need, we must operationally define what “need” means. Are we trying to determine the minimum fat intake that prevents passed away? The minimum fat intake that prevents clinically relevant side effects? The minimum fat intake that is practically feasible? The minimum intake of fats to promote well-being? The minimum fat intake compatible with optimal body function? The answer to each question will be slightly different. In this article, therefore, I would like to focus on some of the main conclusions that set informative limits to daily fat intake goals. I also want to clarify something at the beginning: this article is exclusively for healthy matures without underlying conditions and does not constitute medical advice. For personalized nutritional advice, it is always advisable to consult a qualified professional with appropriate certificates and training.
Prevention of gallstones
The gallbladder is a small organ located in the upper right quadrant of the abdomen. Its main function is to store bile produced by the liver. When we eat a fatty meal, the gallbladder releases bile to facilitate the digestion of fats. Gallstones are small, hard, pebble-like objects that form when the bile in the gallbladder hardens. In many matters, gallstones do not cause visible symptoms. However, if they block a bile duct, they can cause a painful accumulation of bile and possibly require surgical removal of the gallbladder.
It has been known for decades that gallstone formation is one of the most common side effects reported in weight loss clinical trials, in which considerable amounts of weight are lost very quickly (1). Rapid weight loss programs can sometimes cause the liver to release additional cholesterol into the bile, which can increase the risk of gallstone formation. In addition to the risk associated with very rapid fat loss, extreme fat restriction seems to independently increase the risk of gallstone formation. It is possible that this is due to a noticeable reduction in bile release when dietary fats are restricted, resulting in a significant amount of bile sitting for an extended period of time.
In clinical trials of weight loss in obese participants, you might be surprised to see exactly how extreme some of the intervention diets are. It is not particularly uncommon to see diets ranging from 500 to 800 kcal / day with a daily fat intake in the single digits. In a fitness industry where people are sometimes ridiculed for having already suggested to someone to eat less than 1200 kcal/day, these figures seem a bit surprising (especially for participants who often weigh more than 200 pounds!). Not surprisingly, on numerous occasions it has been shown that these types of diets increase the risk of gallstone formation. Fortunately, it seems that this risk can be significantly reduced by adding fat to the weight loss diet, and the amount of fat needed is incredibly low. Based on the best available evidence, an extremely modest fat intake of only 7 to 12 g/day seems sufficient to largely counteract the negative effect of extreme fat restriction on gallstone formation (1).
Intake of essential fatty acids
Another factor that affects the need for dietary fats is our inevitable need for essential fatty acids. Different fatty acids have different physiological roles in the body and the structure of a fatty acid determines its function. Fatty acids consist of a carboxylic acid linked to a hydrocarbon chain, and this hydrocarbon chain can vary in length. As a result, you will often hear about “short-chain”, “medium-chain” and “long-chain” fatty acids. Another structural characteristic that can vary is the number of single and double bonds (Figure 1), which leads to the most recognizable distinction between fatty acids: saturated fats all have single bonds (without double bonds), monounsaturated fats have a double bond (“Mono” means “one”) and polyunsaturated fats have two double bonds
