Macronutrients: Fats

The role of fat in the body includes:

  1. Energy Source. An averaged sized man has over 100,000 Kcal of fat storage. Yup, that’s right! That’s enough to run from Land’s End to John O’Groats and then some
  2. Physical Protection for Vital Organs
  3. Carrier for the Fat-Soluble Vitamins (A,D,E & K)
  4. Hunger Suppression. This is why a lot of fat-free diets are not as successful

Fats are classed in the following way:

fats table

Cholesterol

This is a derived fat, i.e. synthesised by the body and has numerous functions. Our bodies synthesise about 80% of cholesterol whilst the remaining 20% comes from dietary sources. Cholesterol is only found in animal products in our diet, examples include: egg yolks, red meat, shellfish and full-fat dairy and butter. Though these sources directly influence our cholesterol levels, a diet high in saturated fat also increases the body’s own production of cholesterol.

Fat is transported in the blood in the form of Lipoproteins: LDL, aka “bad” cholesterol and HDL, aka “good” cholesterol. What makes LDL bad, is that it becomes attached to artery walls, which promotes atherosclerosis, narrowing of arteries and cardiovascular disease, which is then manifested as high blood pressure, heart disease and strokes. Ways of lowering LDL is by exercise and diet modification. HDL on the other hand, removes LDL from artery walls and can be increased with exercise.

The association between poor health and fat is not as simple as once thought. We were led to believe all fat was bad and as we desperately tried to eliminate it from our diets, we ended up not taking in essential fats and even worse, creating “fat-free” alternatives by substituting fat for sugar.

What we know now, is that there are good and bad fats:

  • Good: Monounsaturated and polyunsaturated fats
  • Bad: Trans-fats aka partially hydrogenated oil
  • Intermediate: Saturated fats

Good Fats

Monounsaturated

Studies have shown that in Greece and other Mediterranean countries, the incidence of heart disease is low despite a high-fat diet. That’s because the main fat in the diet is not saturated animal fat but olive oil, which is mostly monounsaturated fat. Other sources of monounsaturated fats are peanut oil, avocados, nuts, and sunflower oil.

Avocado

Polyunsaturated

Polyunsaturated fats are essential fats; which means they cannot be created by the body and instead have to come from your diet. The two main types are omega-3 fatty acids and omega-6 fatty acids. The benefits of these fats include:

  • Reduce LDL
  • Raise HDL
  • Help prevent and even treat heart disease and stroke
  • Help reduce blood pressure
  • May help reduce inflammation in rheumatoid arthritis
  • Possibly linked with reducing risk of dementia

Sources include oily fish such as salmon and mackerel, flaxseeds and walnuts.

Bad Fats

Trans-fats acids are very bad for your health as they increase LDL and reduce HDL. They have been linked to heart disease, stroke and diabetes. For every 2% of calories from trans-fats consumed daily, the risk of heart disease rises by 23%!

Trans-fats are commonly found in fried food, takeaways, biscuits/cookies, cakes, pastries and hard margarines.

Fried chicken

Saturated Fats: The Big Debate

A diet rich in saturated fats can increase cholesterol. The significance of cholesterol in cardiovascular disease is still being researched. The most recent studies tell us that there is not enough evidence to link saturated fat and heart disease but that replacing these fats with polyunsaturated fat may reduce the risk of heart disease and that replacing them with processed carbohydrates may increase the risk.

Common sources of saturated fat include red meat, whole milk, cheese and coconut oil.

 

This blog is written by friend of Neat, Dr Nick Ambatzis MB BS, MSc (SEM), MRCGP.

Nick is a General Practitioner specialising in Sports and Exercise Medicine. He completed his medical degree at University College London Medical School in 2002. Nick worked for almost ten years as a junior surgeon and spent three years in Trauma & Orthopaedics. He attained a Masters in Sports and Exercise Medicine and subsequently trained as a GP practising in Paddington.

From an early age, Nick has been both a keen cross-country runner and water-polo player, having competed at college level. Nick is also an accomplished ultra-marathon runner, having competed in many cross-country and cross-alpine races, ranging from 50-100 miles. He has also been a Crossfit and Crossfit Endurance coach.