If we don’t want to get fat, we shouldn’t eat fat, right?
Well, the answer is not as simple as that. Yes, gram for gram, fat is the most calorific of the major food groups, containing 9 calories per gram (compared to 4 calories per gram of protein or carbohydrates). For this reason, it's suggested to limit fat intake to 70g per day (95g per day for men), because too much of any kind of fat can contribute to weight gain.
But does this mean we should be avoiding fat altogether? Most certainly not. Here are the reasons why:
It sounds kind of counter-intuitive, but for weight loss or control, you should not be avoiding fats. Here’s why:
- Fats make you feel fuller. Fats take a long time to digest, and when fat hits your intestines, hormones that increase satiety, such as CCK and PYY, are released. In fact, studies have shown that meals rich in omega-3 fatty acids increase the feeling of fullness both directly after, and two hours after, eating the meal (2).
- Low fat foods are often high in sugars. When low (or zero) fat foods are made, in order to make them taste good, manufacturers tend to pump them full of sugar. Sugars raise blood sugar levels, triggering the release of insulin to bring them back down. How does insulin bring sugar levels down? Often by storing them as fat.
- Dietary fat can boost fat metabolism. Diets rich in healthy fats increase the release of the hormone adiponectin from your fat cells (3). Adiponectin plays important roles regulating insulin sensitivity, glucose and fat metabolism, which is why low levels of the hormone are associated with obesity.
This sounds amazing – we no longer have to fear fats! While this is definitely true, it does come with two important caveats:
- Not all fatty foods are created equal - the types of fats we eat are really important. We should aim to eat mono- and polyunsaturated fats, found in leafy vegetables, avocado, nuts, seeds, olive oil, and rapeseed oil. And we should limit saturated and trans fats, found in fatty meats, cheese, lard, cakes, biscuits, pies, and many processed or fried foods, as these can harm our health.
- Fat intake should still be within the UK guidelines. All fats, saturated or not, contain 9 calories per gram. So do add healthy fats to your diet, just not with reckless abandon, as the calories can mount up if you’re not careful.
Absorption of vitamins
Dietary fats are important for the absorption of fat-soluble vitamins (A, D, K and E). Without an adequate amount of fat in our diets, our bodies are unable to effectively absorb and process these vitamins, which are essential for our health.
Essential fatty acids
We can synthesise most fatty acids in our body. However, the ones we can’t make, and therefore must get from our diet, are the polyunsaturated fats linoleic acid (omega-6) and alpha-linoleic acid (omega-3). Omega-3 and 6 are essential for the normal functioning of all tissues in the body – so cutting out fats altogether can affect a whole host of symptoms and disorders.
2. Parra, Ramel, Bandarra, Kiely, Martínez, & Thorsdottir. (2008). A diet rich in long chain omega-3 fatty acids modulates satiety in overweight and obese volunteers during weight loss. Appetite,51(3), 676-680.
3. Von Frankenberg, A., Silva, F., De Almeida, J., Piccoli, V., Do Nascimento, F., Sost, M., . . . Gerchman, F. (2014). Effect of dietary lipids on circulating adiponectin: A systematic review with meta-analysis of randomised controlled trials. The British Journal of Nutrition, 112(8), 1235-50.