Low Fat Diets: Are They The Best Way to Lose Weight?
What’s the truth?
If you want to lose weight, you are probably super-confused about the right approach. One minute you’re told to eat a low carb diet, the next you are told to eat a low-fat diet to lose weight.
Let’s first consider why we are afraid to eat fat, the role of fats in your body and recommended fat intakes.
Then, we’ll be able to answer the $1million question – should you use a low fat diet to lose weight or not?
Why we’re afraid to eat fat
In the G-string leotard-bound, muesli-ridden 1980’s, fat was demonised in a world focussed on calorie intake and beautiful bodies.
Too much fat was seen as an easy way to eat too many calories and a leading cause of overweight and obesity.
This was probably based on research from the 1970’s, which had shown that in some countries like the USA, people were consuming up to 42% of calories from fat!
And of course, fat has a much higher calorific value (9 calories per gram of fat) compared to carbohydrates and protein (4 calories per gram or carbs or protein).
Added to the emerging ‘cholesterol theory’ – that that high cholesterol was a leading cause of cardiovascular disease – and growing levels of overweight and obesity, fat seemed to be the obvious culprit in overweight and cardiovascular disease (1).
6 reasons you need fat
Fast forward to the 21st century, we know that fats play several important roles in the body.
Various types of fat, including cholesterol, play important roles in your body. They:
1. provide up to half of your body’s energy needs
2. are key ingredient in cell membranes, giving them a flexible structure
3. are an element of cholesterol, which is the fuel used in creating hormones
4. supply body fat for insulation against the cold and protecting vital organs
5. are a major component of the myelin sheaths that insulates your nerves
6. allow you to store and assimilate the fat-soluble vitamins A, D, E and K (2).
The challenge is getting the right amount and balance of different dietary fats.
How much fat?
Total fat intake is definitely important.The recommended total daily fat intake should be an average of 70g per day for adults (3), with a range of:
30 – 70g (women and children), and
40 – 80g per day (men)
Your total intake depends on your age, activity levels and body weight status (underweight vs healthy vs overweight).
That is, fat should make up roughly 20 – 30% of your total daily calorie intake (2). The lower values in these ranges may be appropriate for overweight or obese people.
How much fat is 30 – 80g?
For context, here are some typical foods and the amount of fat they contain (4):
– 53g of fat in a 3 piece boxed meal
– 78g of fat in a cup of whole almonds
– 35g of fat in 50g of tasty cheese, 50g of salami and 4 cracker biscuits
– 20g of fat in 2 tablespoons of peanut butter.
As you can see, your fat intake can add up pretty quickly!
It’s good to keep an eye on fat intake, and choose moderate amounts of healthy fats.
Fat balance – not all fats are created equal
There are four main types of fats:
– Monounsaturated fats (e.g. olives, avocadoes, some nuts, peanuts)
– Polyunsaturated fats (e.g. fish, sunflower seeds, walnuts, seeds)
– Saturated fats (e.g. dairy products, meats, fried foods, palm oil, coconut oil)
– Trans fats, a type of saturated fat (e.g. baked goods, pies, pastries, re-used deep fryer oil).
The total fat intake in a healthy diet includes around:
– 1/3 monounsaturated fats
– 1/3 polyunsaturated fats, and
– 1/3 saturated fats (from natural, whole food sources e.g. coconut oil, meats, dairy).
Western diets are usually out of balance, with too many ‘manufactured’ forms of saturated and trans fats, and not enough monounsaturated and omega 3 (polyunsaturated) fats.
An imbalance in dietary fatty acids can lead to:
– increased inflammation
– problems with the immune system
– impaired hormone and brain activity.
These three things can be significant barriers to weight loss
Omega 3 fatty acids are a great addition to your diet, because they lower inflammation in the body, lower blood triglycerides, improve blood vessel elasticity, thin the blood, reduce blood pressure and may help reduce the risk of many health conditions including depression and Alzheimer’s disease. They can also help you lose weight.
Omega 3 fatty acids are found in seafoods, sea vegetables and some nuts and seeds.
So should you use a low-fat diet to lose weight, or not?
Now to the $1million question.
What we know so far is this:
– Dietary fats play several important roles in your body
– There are different types of fats, and balance is important.
– Fatty acid imbalances can be a significant barrier to weight loss.
This is probably enough evidence to suggest you need a moderate amount of dietary fat, with a balance in different types of fat, to function normally and therefore, lose weight.
Does research back this up?
The scientific debate has raged for five decades. And the earlier dietary studies on fat intake and low fat diets show mixed results.
But increasingly, studies are showing that low carbohydrate diets are more effective for weight loss and cardiovascular risk factors than low fat diets (5).
The simple answer?
Eat 2-4 tablespoons of healthy fats each day with your main meals, from whole food sources, to create good health and promote weight loss.
Connect with Expert Melanie White.
1. Strand, Dr R. D. (2005) Healthy For Life. Developing healthy lifestyles that have a permanent side effect of fat loss. Real Life Press, Rapid City, SD.
2. Pitchford, P (2002). Healing with Whole Foods. Asian Traditions and Modern Nutrition 3rd Edition. North Atlantic Books, Berkeley, California.
3. Website: Dieticians Association of Australia; (Accessed 26.11.15)
4. Website: CalorieKing Australia; (Accessed 26.11.15)
5. Bazzano, L. A. Hu, T; Reynolds, K Yao, l; Bunol, C; Liu, Y; Chen, C-S;Klag, M.j; Whelton, P.K and He, J. (2014) Effects of Low-Carbohydrate and Low-Fat Diets: A Randomized Trial. Annals of Internal Medicine, V 161 (5).