Weight gain seems straightforward at a glance. Too much food, not enough exercise, equals weight gain. Right? Well, maybe not.
So how does fat burn fat?
According to researchers at Washington University School of Medicine, dietary fat helps break down existing fat by activating PPAR-alpha and fat-burning pathways through the liver. In simple terms, “old” fat stored in the body’s peripheral tissues – around the belly, thighs, or bottom (known as subcutaneous fat) can’t be burned efficiently without “new” fat to help the process.
Now before you go ahead and order a pizza and some deep-fried chicken, consider this: not all fatty foods are created equal. Most of the fat you eat – especially if you want to lose weight – should come from unsaturated sources, both monounsaturated (MUFA) and polyunsaturated (PUFA).
Unfortunately, these good fats are rare in processed foods (with saturated and trans-fats being the dominant fats chosen), and even if these foods do contain unsaturated fats, their nutrient profiles are often altered due to the many manufacturing processes used.
Instead, you can find good fats in fresh foods such as fish, nuts, leafy vegetables, olive oil and avocadoes – so starting visiting your local farmer’s market!
What do the different fats mean?
Saturated Fatty Acids: This type of fat comes mainly from animal sources such as meat and dairy products, like butter and cheese. Some vegetable oils such as coconut and palm oil also contain saturated fats. Eat limited amounts as part of a healthy diet.
Trans Fatty Acids: These are chemically processed vegetable oils. They are semisolid at room temperature and used in some margarines, as well as fried and processed foods to enhance flavour and shelf life. They are also called ‘partially hydrogenated’ oils and should be avoided wherever possible.
Unsaturated Fatty Acids: These consist of both monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) and are great for overall health – particularly heart health. MUFAs are found in vegetable oils, nuts, seeds, olives and avocadoes, while PUFAs are found in vegetable oils, fish and seafood. Omega-3 and Omega-6 fatty acids are two PUFAs that can only be obtained through diet and are called ‘essential fatty acids’.
How is fat different from sugar?
Another benefit of fat is its digestion rate. It isn’t the easiest nutrient to digest and as a result it keeps us fuller for longer. On the other hand, sugar is quickly processed by the body. I often call sugar the body’s quick energy source – great in those necessary situations, but not so much for those of us sitting on the couch re-watching our favourite episodes of Friends.
As the body can only use so much glucose at a time, and the liver can only work so hard, this results in most of our sugar being stored as fat. Not only does a majority of sugar get stored as fat, certain sugars can cause the body to develop a resistance to the hormone leptin – also known as the fullness hormone.
Leptin is secreted by fat cells to signal how much fat is stored for a rainy day. When the brain senses increased leptin, it senses that we have enough fat and we don’t need to eat as much. What happens when we become resistant to leptin, is that the brain thinks the body is starving and we eat more and burn less as a result!
How do good fats affect our metabolism?
Good dietary fat not only helps to protect our organs and maintains cell membranes; good fats can also help to support hair and skin health, as well as our metabolic rate.
In a Clinical Science 2011 study, researchers examined the effects of eight weeks of PUFA supplementation in middle aged adults and found that the fat increased protein concentration and the size of muscular cells in the body. Some previous studies have also found Omega-3 fatty acids to stimulate muscle protein synthesis in older adults.
Now this doesn’t mean you will bulk up suddenly and turn into the Hulk. It just means that you develop more lean muscle which may lead to an increased metabolism and burn more fat as a result.
A challenge for you this week is to substitute something sweet with some good fats. For myself, I have swapped my honey sandwiches for avocado and tomato filling. What are your plans for the week?
In good health.
- Read more on the Washington University study here: http://news.wustl.edu/news/Pages/5258.aspx
- Read more on the Clinical Science 2011 paper here: http://www.clinsci.org/cs/121/cs1210267.htm