Dietary fat is one of the three main nutritional substances (as well as carbohydrates and proteins) that provide us with energy to perform our daily functional needs. Nutritional fat received bad press in the 1990s and 2000s after research stated that it would clog arteries, increase the risk of heart disease and increase body fat levels. But the 2010s produced a new wave of information that showed dietary fats to be good for you and that it was sugar that actually provided noticeable weight gain. As the initial impact and scaremongering of these findings has calmed over the years, we now know that both views on fat are true to some extent.
Firstly, nutritional fat is a dense source of energy for the body – it has a higher calorie count per gram compared to proteins or carbohydrates (9 calories per 100g compared to 4 calories per 100g). As well as providing the body with a source of energy, fats are essential for growth and development of our cells with some bodily functions unable to occur without a diet containing fat. The digestion and use of fat in the body enables full functioning of the nerves and brain, it helps maintains healthy skin and other tissues, it is essential for transporting fat-soluble vitamins (A, D, E and K) through the bloodstream and for forming naturally occurring steroid hormones that regulate many bodily processes.
Eating fat will make you fat
Yes and no. Firstly, it’s necessary to say that all foods are composed of different levels of all three nutritional components (carbohydrates, fats and proteins) and so any analysis of one individual component is comparable with the other two individual analyses. In practice, knowing how much of each component is present within a food type will allow you to understand how and to what extent the food substance will have an effect on your body.
To address the ‘no, eating dietary fat won’t make you fat’ message of the 2010s. Fat does not create the same hormonal response as sugar, a carbohydrate, which can look to immediately and automatically create more stored body fat upon consumption. This response to sugar occurs through the hormone ‘insulin’ which is secreted in high quantities when high sugar foods are consumed. Insulin’s primary function is to remove sugar from the bloodstream sending it to muscles to allow you to be active and removing it from the blood to avoid harmful levels.
However, unless this sugar is used up quite immediately through activity or it is needed to replenish depleted muscle glycogen levels after strenuous exercise, the body looks to store this quick release excess energy as body fat. The body simply thinks ‘this is a high source of energy I’ve been given, this will be useful, but I don’t need it now so I’ll store it for later’. For many people, ‘later’ never comes in terms of strenuous exercise and body fat storage continues to build.
Dietary fat does not facilitate this hormonal response and thus its consumption does not provide an immediate automatic internal feedback mechanism to store body fat as sugar does.
However, because of its high calorific value compared to proteins and carbohydrates as previously mentioned, it has the propensity to cause body fat to be stored through another method. Over consumption!
To put on body fat, you must consume more calories in a day than you expend. The high calorie content of nutritional fat means that it takes less volume of food to reach your daily calorie input/output equilibrium compared to consuming carbohydrates and proteins. Thus, the reason that dietary fat is often viewed as a body fat gaining substance is because consuming it puts you closer to your daily calorie limit compared to eating the comparative volume of carbohydrates or proteins – remember it has over double the calorific content (9 calories/g compared to 4 calories/g).
Basically, nutritional fat is a higher risk substance than carbohydrates and proteins for staying under you daily calorie output level. A big bowl of porridge oats (100g with water) in the morning will provide you with 380 calories; just a small half cup (50g) of nuts – seen as a casual snack to the non-informed – can provide you with 500 calories!
Fats are bad for you and clog up your arteries
Again, it is necessary to state that all food is bad for you in high quantities. But, yes, some fats are inherently detrimental to good health and fitness in their make up and can clog your arteries and increase the risk of heart disease without adhering to caution by raising blood cholesterol levels – fatty deposits that build up in blood vessels obstructing the flow of blood. These ‘bad’ fats are saturated fats and trans fats.
Saturated fats are found in foods such as fatty cuts of meat and other meat-derived products, as well as unskimmed dairy products, all of which can combine or be intrinsic parts to making manmade foods taste good, addictive for some and be regressive for your health.
Trans fats are mainly found in manmade foods, fried foods and fast foods. These tend to be seen as the worst dietary fat as we mainly find them in foods where chemical or mechanical processing has occurred. Without going into too much detail, trans fats are created when ‘natural’ fats – saturated, unsaturated, polyunsaturated – are pumped with hydrogen and made worse for you. They can be known as hydrogenated fats. Avoid or at the very least significantly limit these fats to promote long-term health, fitness and vitality.
However, some fats are inherently good for you. These come in the form of unsaturated fats – monounsaturated and polyunsaturated. Eating unsaturated fats can improve blood flow by removing the ‘bad’ (LDL) cholesterol blockages in the arteries, increasing the good (HDL) cholesterol levels (yes, one type of cholesterol is good for you and actually scavenges the ‘bad’ cholesterol) and can promote a healthy heart and cardiovascular system. Both mono- and polyunsaturated fats are essential to consume for this to occur. Monounsaturated fats can be found in olive and rapeseed oil, peanuts and avocados. Polyunsaturated fats are mostly found in plant foods such as nuts, seeds, vegetable oils and in cold-blooded sea-foods. Omega-3 and omega-6 are two classes of polyunsaturated fat that provide essential fatty acids that benefit our muscular, cellular, vascular and neurological processes as stated earlier. Oily fish (e.g. herring, mackerel and salmon) is a great source of omega-3. Rapeseed oil, walnuts and seed mixes are a great source of omega-6.
Consuming fats and sugar together makes you more likely to develop diabetes
As I wrote earlier, sugar consumption initiates a hormonal response in the pancreas to release the hormone insulin. Insulin looks to remove sugar from the bloodstream to help regulate the balance of the blood’s consumption and to shuttle sugar into the muscles so they can function efficiently. Again, as we now know, when we consume fat, insulin isn’t secreted to the same extent – this is a natural process. However, when you consume fats and sugar together, the dietary fat blunts the insulin response. When this happens, the pancreas works even harder to produce insulin to remove the sugar from the blood, turning your physical state from active or hyperactive to slow and lethargic.
The more resistance there is over time due to continued consumption of fat and sugar together, the harder the pancreas works to create the desired process of sugar removal until in the end it cannot efficiently cope with removing the sugar – this is known as pre-diabetes. When blood sugar levels remain high without the appropriate amount of insulin available to remove the excess sugar, over time there will be damage to nerves and blood vessels, potentially leading to heart and brain complications, organ failure and amputations. At the very least, constantly high sugar levels from insulin resistance promotes increased nervousness, behavioural sensitivity and hyperactivity as well as continual fat gain. When the hormonal response of the pancreas has continued minimal impact on the sugar levels, diabetes is diagnosed.
In both a pre-diabetes and full Type 2 diabetes state, you can look to increase insulin sensitivity and improve your current insulin response and level of health. You can do this by:
- Decreasing your carbohydrate consumption overall and eating only complex carbohydrates around times of activity.
- Consuming carbohydrate sources high in fibre such as in fruit and vegetables have also been shown to return the insulin response to natural levels. Even though some fruits are higher in sugar, the sugar is natural and the high fibre content also reduces the sugar’s impact.
- Ensuring that you do not regularly consume foods or meals with both high sugar and high fat levels – these can be found in many desserts, processed foods and fried/fast foods – and ensure that the majority of the fat that is consumed is an unsaturated option.
An example of a good progressive meal towards increasing insulin sensitivity would be a roast salmon salad with spinach, tomato, olives, broccoli and carrot, or porridge oats cooked with water and topped with flaxseeds, blueberries and greek yoghurt.
So, fats can be extremely good for you and are essential to a healthy life. Some fats are bad for you inherently due to their make up and can clog arteries. All fats (and all food types) are bad for you when over-consumed for a long period of time.
Dietary fats provide ~9 calories per gram
The average man should eat no more than 30g of saturated fat a day.
The average woman should eat no more than 20g of saturated fat a day.
TIP: Don’t go overboard with your new found knowledge of ‘good’ fats. A meal of mackerel, salmon, olive oil, cottage cheese, avocados, seeds, edamame and walnuts in a salad, whilst all ‘good fats’ is in danger of being too much fat which will increase calories consumed quite substantially taking you closer to that daily calorie input/output balance quicker. However ‘good’ the calories are for your health, you are likely to put on body fat when consuming over your daily calorie limit. Have a few fats at a time, and spread them over the day.
AT THE SHOPS
Foods high in saturated and trans fats (to be limited)
Butter and lard – any food made with these too (desserts, cakes, sauces)
Cream and ice cream
Pastry – sweet and savoury
Steak (rib-eye and sirloin are fattiest cuts)
Pork – belly, bacon, sausages especially
Cheese – barring some cottage, ricotta and fat-reduced cheeses
Burgers, pizzas, fried foods, ready meals, fast foods, manmade snacks
Foods high in monounsaturated fats (good fats)
Olive, peanut, canola, sunflower, vegetable and sesame oils
Nuts and nut butters – almond, peanut, pistachios, hazelnuts
Seeds – sesame, pumpkin, flax, sunflower
Some fish – herring, halibut, sablefish, mackerel
Foods high in polyunsaturated fats (good fats)
Walnuts, peanuts, peanut butter
Canola oil, olive oil (extra-virgin is most beneficial)
Salmon, tuna, sardines, trout, herring
Sunflower, sesame, chia seeds
Soybean (tofu, edamame raw bean, oil)
Director, Head of Fitness and Nutrition