Are low-fat diets healthy?
Read our expert nutritionist's guide on the health implications of following a low-fat diet, along with tips for cutting down on ‘bad’ fats
You probably already know that consuming too much fat is bad for you, but did you know that too little of the right kind can leave you nutrient deficient and lacking in energy too? Registered nutritionist Jo Lewin explains more.
Following a low-fat diet? Browse our collection of low-fat recipes for inspiration. Also check out our guide on low-GI diets, plus discover our full range of health benefit guides.
What is fat and why is it important?
Fat, like carbohydrates and protein, is a macronutrient needed by the body to build cell membranes, make nerve tissue and hormones, and aid the absorption of fat-soluble nutrients, including vitamins A and D. Our bodies use fat as energy and store any excess for future use; this stored fat acts as an insulator and helps cushion vital organs, bones and other tissues, protecting them from damage.
Although eating too much fat can be unhealthy, there are certain types of fat we must get from our diet because they’re essential to our health.
What are the different types of fat?
There are three main types of fat – saturated, monounsaturated and polyunsaturated – and they all play different roles in the body.
Frequently vilified, having been associated with cardiovascular disease and high cholesterol, saturated fat is found in red meat, butter, cheese, burgers and sausages as well as ghee, coconut and palm oil.
A diet high in these fats has historically been associated with an increase in blood fats, including triglycerides, as well as an increased risk of obesity, heart disease, type 2 diabetes and stroke. More recent studies, however, are now suggesting that some fats such as those found in fermented dairy such as cheese, kefir and yogurt do not appear to be as harmful, and may in fact have a positive effect on heart health. This may be because other nutrients in dairy, like calcium, or the fermentation process itself may modify the effects of saturated fats in the body.
Monounsaturated fat, like that found in olive, groundnut and cold-pressed rapeseed oils, nuts (such as almonds, cashews, hazelnuts, peanuts and pistachios), olives and avocados are particularly good for heart health. These fats may help manage cholesterol levels.
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 may help to prevent your arteries becoming blocked and may lower blood pressure.
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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. Discover more sources of omega-3 fats.
Which are the fats I should minimise?
Trans fats, also known as hydrogenated fats, are usually found in processed foods like pies, pastries and cakes and in takeaways. Trans fats have been linked to high cholesterol levels and an increased risk of heart disease and cancer.
Read labels on any foods you haven't cooked from scratch, and try to avoid those containing ‘hydrogenated’ oils.
For more information on trans fats, visit the NHS website.
How much fat should I eat?
UK guidelines recommend that our total fat intake should not exceed 35% of our total daily energy (calorific) needs with the maximum for saturated fats being 11%. For the average, moderately active, adult female this equates to 70g of total fat and 20g of saturated fat. The UK Government also recommends that no more than 5g per day should be from trans fats.
By reducing the unhealthy saturated and trans fats in our diet and replacing some of these fats with the healthier unsaturated fats, you may achieve a better balance for our heart and overall health.
Read our guide on how much fat you should eat a day.
Why choose a low-fat diet?
Those trying to lose weight, manage cholesterol or with certain health conditions including type 2 diabetes or multiple sclerosis may aim to reduce the total amount of fat they consume.
What counts as a high fat or low-fat food?
When shopping for packaged foods, compare nutrition labels so you can choose foods that are lower in fat. The best way to do this is refer to the 'per 100g' column on the nutrition label.
Some packaging also carry the traffic light colour coding system. Red reflects high levels of fat and saturated fat, while green indicates low levels – aim to eat red-coded foods occasionally and green-coded foods more frequently.
Visit the NHS Choices pages for more information on food labelling.
Is a low-fat diet healthy?
A diet that provides insufficient amounts of fat may lead to dry skin, hair loss and a weakened immune system as well as lead to:
Very low intakes of fat limit the amount of fat-soluble vitamins A, D, E and K we absorb. 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.
Poor brain function
Dietary fat, especially the essential fatty acids, are important for brain health and development. Low levels of unsaturated fats may impact cognitive function and mood.
Women who don’t get enough fat in their diet and have a body fat composition below optimum, may observe disruptions to their menstrual cycle and may even experience fertility issues.
Weight management issues
In the short-term limiting your intake of any food or macronutrient may help you lose weight. However, although fat is high in calories, providing 9 kcals for every gram eaten compared to 4 kcals from protein or carbs, its association with weight gain is not clear. Numerous studies fail to support low-fat diets over other interventions for long-term, sustained weight management.
Tips for cutting back on fat
If you’re looking to improve the balance of fat in your diet here are some practical steps to take:
- Choose 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 trim off 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 such as 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
Following restrictive, low-fat eating plans or diets may help you lose weight in the short term, but once you go back to your old eating habits, your body will be more prone to storing fat and the weight will go straight back on.
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. Find inspiration with these low-fat options.
Healthy salads with low-fat dressings:
Chargrilled turkey with quinoa tabbouleh & tahini dressing
Barbecued fennel with black olive dressing
Coleslaw with tahini yogurt dressing
Spicy tuna & cottage cheese jacket
Ricotta & basil pizza bread
Classic recipes with lower calories:
Herby pork with apple & chicory salad
Low-fat turkey bolognese
Chicken with lemon & courgette couscous
Heart-healthy fish recipes:
Thai-style steamed fish
Zesty haddock with crushed potatoes & peas
Cod & olive tagine with brown rice
Discover more low-fat recipes.
Food Standards Agency
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).
Jo Lewin is a registered nutritionist (RNutr) with the Association for Nutrition with a specialism in public health. Follow her on Twitter @nutri_jo.
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