Spotlight on... low-fat diets
You probably already know that consuming too much fat is bad for you, but did you know that too little of the good kind can leave you nutrient deficient, with high cholesterol and lacking in energy? Nutritionist Jo Lewin explains.
A certain amount of fat is required for health. It is needed to absorb certain fat-soluble nutrients, manufacture cell walls and produce hormones. Fat is a valuable source of energy, and provides essential fatty acids that the body cannot make itself. However, not all fats are equal in terms of their effects on the body. Eating the right kinds of fat can help to protect you from heart and circulatory problems, but too much of other types can be detrimental to health. There are three main types of fat – saturated, monounsaturated and polyunsaturated – and they all have different roles to play in the body.
Saturated fat is frequently vilified, as it has been associated with cardiovascular disease and high cholesterol. Red meat, butter, cheese, burgers and sausages are high in saturated fat, as is ghee and coconut and palm oils. A diet high in saturated fat can increase blood fats, including triglycerides, as well as increase your risk of obesity, heart disease, type 2 diabetes and stroke. However, recent studies are now suggesting that dairy products such as cheese, kefir and yogurt do not appear to be as harmful as once thought, and may in fact have a positive effect on heart health. This may be because other nutrients in dairy, like calcium, may modify the effects on blood fats such as triglycerides.
Monosaturated fat, like that found in olive, groundnut and cold-pressed rapeseed oils, nuts (such as almonds, cashews, hazelnuts, peanuts and pistachios), olives and avocados is particularly good for heart health. These fats can help lower LDL cholesterol.
Polyunsaturated fats are found in corn oil, sunflower oil, nuts and seeds (such as walnuts, pine nuts, sesame seeds and sunflower seeds). There are two main types of polyunsaturated fats: omega-3 and omega-6. These are termed 'essential fats' as they cannot be made in the body and need to be obtained through the foods we eat. Polyunsaturated fats help to prevent your arteries becoming blocked and may lower blood pressure.
Typically, we obtain a high proportion of omega-6 fatty acids in our Western diet and low levels of omega-3. But, it is important that we eat adequate amounts of omega-3 – key foods are oily fish, such as salmon, herring and sardines, as well as nuts such as walnuts and seeds such as chia and flaxseed. If the balance of these fats is in favour of omega-6 fatty acids, then it is likely to promote inflammatory conditions.
Sources of omega-3:
- Oily fish – salmon, mackerel, trout, sardines, herring
- Pumpkin seeds
Sources of omega-6:
- Oils – corn, safflower, soya bean
One portion of oily fish = approximately 140g (cooked weight).
It is recommended that we eat two servings of fish per week, at least one of which should be the oily variety. If you don't like oily fish, you can get omega-3 fatty acids from vegetable sources, such as flaxseed, nuts and seeds; however, it remains uncertain if the omega-3 in these foods brings the same heart-healthy benefits as those in oily fish. If you are considering an omega-3 supplement, make sure you discuss it with your doctor to ensure there are no contraindications with other drugs you might be taking.
A note on trans fat...
Trans fat is also known as hydrogenated fat. This is commonly used in manufactured food products such as shop-bought pies, pastries and cakes, favoured for their palatability and long shelf life. Trans fats are linked to high cholesterol levels and an increased risk of heart disease and cancer. Read labels on any foods you haven't cooked from fresh, and try to avoid those containing hydrogenated oils. For more information on trans fats, visit the NHS website.
Those who are trying to lose weight, lower cholesterol or have concerns about the amount of fat in their diets may want to reduce the total amount of fat they consume.
The recommended daily amount (RI) of total fat is 70g for men and women.
Within this amount, many people eat too much saturated fat. We should eat no more than 20g of saturated fat per day.
When shopping, compare nutrition labels so you can choose foods that are lower in fat. Use the 'per 100g' column to compare.
Some packaging also uses the traffic-light colour coding to reflect saturated fat levels. 'Red' reflects high saturated fat, while 'green' indicates low saturated fat. Aim to eat 'red' foods occasionally and 'green' foods more frequently. Visit the NHS Choices pages for more information on food labelling.
So what counts as high fat and low fat?
- High: more than 17.5g of fat per 100g (packaging may be colour-coded red).
- Low: 3g of fat or less per 100g (packaging may be colour-coded green).
Look out for 'saturates' or 'sat fat' on the label: this tells you how much saturated fat is in the food.
- High: more than 5g saturates per 100g (packaging may be colour-coded red).
- Low: 1.5g saturates or less per 100g (packaging may be colour-coded green).
If the amount of fat or saturated fat per 100g is in between these figures, that's a medium level, and packaging may be colour-coded amber.
Tips for cutting back on fat
- Where possible, choose the healthier mono- and polyunsaturated fats instead of saturated to help protect your heart. Enjoy small amounts of butter and coconut oils while focusing on olive or rapeseed oils. Minimise your intake of lard, ghee and palm oils.
- Choose lean cuts of meat and make sure you trim any excess fat and remove the skin from chicken or turkey.
- Use a spray oil or measure it out with a teaspoon instead of pouring oil straight from the bottle.
- Read food labels to help you make choices that are lower in total fat and saturated fat.
- Use alternative cooking methods such as baking, boiling, grilling, poaching, microwaving or steaming instead of frying or roasting so you do not need to add extra fat.
- Cut down on processed foods such as crisps and biscuits and avoid fried foods like samosas, bhajis, chips and doughnuts. Replace these with healthier fruits and vegetables.
- Make your own salad dressings using ingredients such as balsamic vinegar, low-fat yogurt, lemon juice and herbs.
- Choose lower-fat dairy products such as semi-skimmed or skimmed milk, low-fat yogurt and crème fraîche.
- Try leaving out or using less butter and spreads on bread when making sandwiches. Use nourishing foods like avocado, which is rich in monounsaturated fats.
- Cottage cheese, ricotta and light soft cheese are low-fat options. Keep your portions of cheese small or opt for less of the strong-flavoured varieties, such as parmesan – a little goes a long way.
*always check labels
Very low intakes of fat limit the amount of fat-soluble vitamins A, D, E and K and essential fats in our diet. This group of fat-soluble vitamins plays an essential role in vision, skin, the immune system, hormone synthesis, bone health and the nervous and reproductive systems. A lack of fat in the diet will lead to reduced absorption of these essential vitamins.
However, all fats are high in calories, with 9 kcals for every gram eaten. So, it is important for our weight and health not to eat too much. By reducing the unhealthy saturated and trans fats in our diet and replacing some of these fats with the healthier unsaturated fats, we will be getting a better balance for our heart and overall health.
Things to watch out for
Just because a food packet contains the words 'low-fat' or 'reduced-fat' doesn't necessarily mean it's a healthy choice. The lower-fat claim simply means that the food is 30% lower in fat than the standard equivalent. So if the type of food in question is high in fat in the first place, the lower-fat version may also still be high in fat. For example, a lower-fat mayonnaise is 30% lower in fat than the standard version, but is still high in fat.
Also, foods that are marked 'low-fat' or 'reduced-fat' aren't necessarily low in calories. Often the fat is replaced with sugar, and the food may end up with the same, or an even higher, calorie content. To be sure of the fat content and the calorie content, remember to check the nutrition label on the packet.
Following restrictive, low-fat eating plans or diets may help you lose weight in the short term, but once you go back to old eating habits, your body will be more prone to storing fat and the weight will go straight back on again. If you want to lose weight, concentrate on eating a balanced diet, drinking sensibly and step up the amount of exercise you do. Be cautious of 'faddy' calorie counting and crash diets.
Most recipes can be lowered in fat by replacing ingredients or reducing the quantity of fat used.
Tasty, healthy salads with low-fat dressings:
Chargrilled turkey with quinoa tabbouleh & tahini dressing
Barbecued fennel with black olive dressing
Coleslaw with tahini yogurt dressing
This article was last reviewed on 5 July 2019 by Kerry Torrens.
A qualified nutritionist (MBANT), Kerry Torrens is a contributing author to a number of nutritional and cookery publications including BBC Good Food magazine. Kerry is a member of the The Royal Society of Medicine, Complementary and Natural Healthcare Council (CNHC), British Association for Applied Nutrition and Nutritional Therapy (BANT).
All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact your local health care provider. See our website terms and conditions for more information.