Sugar makes you hungry, fat tells you that you’re full
If only our mothers had given us that advice… there’d probably be no obesity epidemic, health insurance rates would be a lot cheaper, and all that money spent on diet books could have been used for something a lot more fun, like skiing.
So it’s time to get over our fear of eating fat. Where does this fear come from? Mainly from erroneous assumptions, incomplete data analysis, and just plain closed-mindedness.
Cholesterol is a lipoprotein, part fat (“lipo-” is latin for fat) and part protein. Just like the human body, it comes in high-density (muscular – muscle is made of protein), and low-density (fat) forms. Think of density solidity – muscle is more solid than fat (muscle jiggles less than fat) because protein is more solid than fat. The high density (protein, muscle) type is the good stuff (low risk of heart disease), while the low density (fat) type is bad (high risk of heart disease).
Fat serves a lot more purposes than just energy storage.
In the 1980s, Jeffrey Friedman, a molecular biologist at Rockefeller University was among the first to report that fat produces a hormone, called leptin (from the Greek leptos, meaning thin) which tells you when to stop eating by signaling your brain that you are full. Leptin also has a beneficial effect on t-cells, assisting in wound healing and strengthening the immune system.
saying “fat makes you fat” is like saying “blueberries make you blue”
If science teaches us anything, it’s that most things in nature are not the way they seem (the sun seems to rise and set, but actually the earth is spinning at about 1000 mph!). Sparing you the details of fat metabolism, the bottom line is that when you eat fat it doesn’t become fat in your body but is actually used as an energy source by all the cells of your body. Because it is absorbed and metabolized slowly, and it provides such a versatile energy source, it signals the body that food in plentiful and there is no need to prepare for lean times or starvation.
When you eat fat it also doesn’t become the fat that clogs your coronary arteries. Just like cholesterol there are different types of fat that have different effects. The subcutaneous (under the skin) type is the good kind that produces the “I’m full” hormone and strengthens the immune system, the deep belly (“visceral”) type is the bad guy that leads to heart disease and diabetes.
The production of bad fat occurs in the liver, which is completely bypassed by fat absorption and
metabolism. But guess what is metabolized in the liver and causes the accumulation of deep belly fat as well as the bad LDL cholesterol that causes heart attacks? You might be surprised to hear that it’s sugar! Fructose, to be more precise, which is the chemical that gives fruits and desserts their sweetness.
These triglycerides, cannot be absorbed by the intestine. They are broken down into mono- and di-glycerides plus free fatty acids (but no free glycerol) by pancreatic lipase, which forms a 1:1 complex with a protein called colipase (also a constituent of pancreatic juice), which is necessary for its activity. The activated complex can work only at a water-fat interface. Therefore, it is essential that fats are first emulsified by bile salts for optimal activity of these enzymes. The digestion products consisting of a mixture of tri-, di- and monoglycerides and free fatty acids, which, together with the other fat soluble contents of the diet (e.g. the fat soluble vitamins and cholesterol) and bile salts form mixed micelles, in the watery duodenal contents (see diagrams on the left). The contents of these micelles (but not the bile salts) enter the enterocytes (epithelial cells lining the small intestine) where they are resynthesized into triglycerides, and packaged into chylomicrons which are released into the lacteals (the capillaries of the lymph system of the intestines). These lacteals drain into the thoracic duct which empties into the venous blood at the junction of the left jugular and left subclavian veins on the lower left hand side of the neck. This means that the fat soluble products of digestion are discharged directly into the general circulation, without first passing through the liver, as all other digestion products do. The reason for this peculiarity is unknown.
According to Sylvia Tara, author of “The Secret Life of Fat”, good fat can fight bad fat by making a hormone called adiponectin, which guides circulating fats in our bloodstream into the subcutaneous tissues where they can do the good work of controlling appetite and improving immune function and wound healing. Guess how else you can produce the beneficial hormone adiponectin? That’s right – exercise. If you don’t have time to spend several hours a week at the gym, new studies show that you can get the same benefits from just a few minutes of interval training three days a week.
What this means is that your fear of fat is completely unfounded. It doesn’t make you fat and it doesn’t cause heart disease. In fact, healthy fats (mono-unsaturated and omega-6 and 3 especially) not only fill you up so you eat fewer calories, but they also produce hunger-controlling hormones and play a positive role in immune function, wound healing, and the prevention of heart disease. Fat actually makes you thin and healthy! It’s sugar that makes you fat and prone to heart disease and diabetes.
So the simple take home message is eat more of these:
- almonds, avocados, olives, and their oils
- oily fish like salmon
- milk – especially coconut or almond milk
Basically all the stuff our Moms thought made us fat!