There is no agreed figure or percentage in answer to the question “how much fat should I eat?” Ask different nutritionists, personal trainers, doctors, or dietitians, and you’ll get different answers. What is certain is that fat is a vital macro-nutrient which serves many functions in the body, so there’s always a danger of eating too little fat.
But there’s also a danger of eating too much, as excess fat is stored in the body as adipose tissue ( another term for body fat). So how much is too much? As a personal trainer, I advise my London clients to eat a healthy balance of protein/fat/carbs in roughly the proportion 25% protein, 30% fat, and 45% carbs, as a percentage of total daily calories.
So for a adult male, a good baseline daily calorie intake is around 2,500 calories. 30% fat would be 750 calories from fat, which equates to 83g of fat a day. And for an adult female, 2,000 calories is a good daily target, so 30% of these calories from fat equates to 600 calories, which is around 67g fat per day. Remember that 1 gram of fat is 9 calories, 1 gram of protein is 4 calories, and 1 gram of carbs is also 4 calories.
I would say too much fat is 5% above these calorie figures, and over; and too little fat in your diet is around 10% below these calorie figures, and under.
But that’s not the end of the story, because not all fats are the same. You need a balance of saturated fats, monounsaturated fats, and polyunsaturated fats, for optimum health. The only fat you should avoid completely is hydrogenated fats, which are manufactured by the food industry as a component of many junk foods, ready meals, takeaways, and junk-confectionery. Avoid these like the plague. More about trans fats in a future blog post.
All fats contain three chemical elements: carbon, oxygen, and hydrogen. But different types of fats have different combinations of these three elements.
You might be surprised to learn that all foods that contain fat, contain at least some saturated fat, so it’s impossible to eliminate saturated fat from your diet, and it would be very bad for your health to try, because it would mean cutting your total fat intake to dangerously low levels. Olive oil, for example, is 14% saturated fat, 75% monounsaturated fat, and 11% polyunsaturated fat.
These fats are called saturated because they’re saturated with hydrogen atoms. We are told to limit saturated fats to around 10% of our total calories, and this is about right I think. However, evidence is emerging that saturated fat is not as big an enemy as at first thought. Hydrogenated fats are far more damaging to the body, being artificially manufactured fats. And refined/processed carbohydrates are more of a health risk than saturated fat, due to their effect on blood sugar levels.
Breast milk is very high in saturated fat, and this is known to be good for babies physical development. So the demonisation of saturated fat should be reviewed. Zoe Harcombe in her book ‘The Obesity Epidemic’ goes as far as to say that saturated fat is not a problem, the problem is refined/processed carbohydrates, and hydrogenated fat (ie artificial trans fats). “How can anyone who knows about nutrition put low fat and healthy diet in the same sentence?” Zoe Harcombe says in her book.
Olive oil is the best example of a food high in monounsaturated fat, also almonds, cashew nuts and avocados. Unlike saturated fat, monounsaturated fat is liquid at room temperature. Whereas saturated fats are saturated with hydrogen atoms, monounsaturated fats have one point of unsaturation, and polyunsaturated fats have two or more points of unsaturation in their chemical structure.
There are two kinds of polyunsaturated fats, omega 3 and omega 6. Examples of foods rich in omega 3 are oily fish such as salmon and mackerel. And omega 6 rich foods include nuts and seeds, egg yolks, and vegetable oils.
Why do we need fat in our diet?
Fats (in the form of amino acids), along with carbohydrates (in the form of glucose), are an important source of energy. But fats are needed for much more than just energy. They form vital parts of many of our body’s structures, including the brain, cell walls, and skin. Body fat cushions our vital organs, and helps keep us warm.
Fat is also vital for absorbtion, storage, and utilisation of the fat soluble vitamins: A, D, E, and K. These vitamins play many roles in the body.
We need vitamin A for night vision, to fight infection, and to make cells, skin, and bone. All pretty vital for a healthy body.
We need this vitamin for absorption of the minerals calcium and phosphorus, both needed for healthy teeth and bones. Vitamin D is found in oily fish and eggs. Non-fish vegetarians would need 26 eggs a day to get adequate vitamin D from their diet, according to Zoe Harcombe in her book The Obesity Epidemic.
This is not just one vitamin, but a whole family of fat-soluble vitamins. Its key role is as an antioxidant. It’s also an anti blood-clotting agent (useful for the flow of blood in the bloodstream), and it also protects the skin. The best source of vitamin E is sunflower seeds.
Blood clotting and wound healing are the key roles of vitamin K. There are two types of vitamin K, K1 and K2. K1 is found in green leafy veg, and avocados. K2 is found in red meat, eggs, and hard cheese. Vitamin K deficiency leads to bleeding gums, nosebleeds, easy bruising, heavy periods in women, and poor clotting/healing of cuts.
So you can see how vital fat is in our diet. As a personal trainer, I’m always telling my London clients to avoid low fat diets, as they do you far more harm than good.
The fats I’ve discussed are all triglycerides, which accounts for 95% of all fats. But there are two more classes of fats: phospholipids, and sterols (of which cholesterol is the most familiar one). All these classes of fats are collectively termed ‘lipids’. Now you know more about fats than the vast majority of the population!
In future blog posts I’ll focus on cholesterol, and also trans fats (hydrogenated fats).