Eat Fat to Melt off the Fat?
There is no question about it; low fat diets work, but are not without problems. While dietary fat intake does have a more direct pathway for storage (.i.e. body fat), all that really matters at the end of the day is how many total calories we have eaten. Fat loss is actually a very simple equation: (energy intake) – (energy expenditure) = (weight loss or gain). While there are many other factors, at the end of the day this is all that matters. Our body fat stores are analogous to a bank account- we are constantly making deposits and withdrawals on a continual basis- deposit more than we withdraw and we gain fat, withdraw more than we deposit and we loose fat. Of course, if it were actually this simple I’m sure a couple of questions come to mind:
Most weight loss diets fail not because of a lack of adherence to the weight loss diet but from the nature of the diet itself. We have been brain-washed by the ‘low fat’ craze in the media to eat a low fat diet to burn off the extra body fat. This type of weight loss diet is not suited for all people. Many people who have problems losing weight on a weight loss diet fail to do so not because of calorie intake according to the equation above, but from storage of those calories in the wrong place (i.e. body fat). So we are really dealing with a calorie storage problem, rather than a calorie intake problem. Low fat diets tend to consist of higher proportions of carbohydrates, many of which are typically high glycemic index (GI for short). These high GI carbohydrates tend digest more quickly, raising blood sugar more rapidly and to higher overall levels. This is where insulin comes in.
Insulin’s job is as a storage hormone; it is released by the pancreas in response to an increase in blood sugar and acts by transporting the sugar, in the form of glucose, into muscle cells to be stored as glycogen (good!) or fat cells to be converted to triglyceride and stored as body fat (bad!). Under ideal circumstances, the muscle cells will preferentially take up glucose compared to body fat. With a high-carbohydrate diet however, blood sugar tends to rise quickly followed by a massive increase in insulin. Insulin basically desensitizes the muscle cells to the action of insulin; when muscle insulin sensitivity decreases, more and more of that blood glucose gets converted to triglyceride and shuttled into body fat stores. When people start on a weight loss diet they are typically out of shape and carrying a higher level of body fat; under these conditions muscle-cell insulin sensitivity is down, hence the “storage problem”. Even at a reduced calorie level more energy is being diverted into body fat relative to muscle tissue- the body is basically feeding the body fat and starving the muscles! A high-carbohydrate diet, for this reason, can actually encourage muscle loss in those who choose to follow this type of low fat/high carb diet. These people may even be able to sustain a decent amount of weight loss at first, but the weight loss is not ideal; body fat either increases or stays the same at the expense of hard-earned muscle tissue.
Obviously, calories need to be reduced in order to loose weight, but we need to be picky about where these calories come from in order to build muscle and loose fat. We want our weight loss diet to cause a nice, steady and slow release of insulin so that muscle preferentially takes up the glucose compared to body fat. We will accomplish this in two ways:
Choosing low glycemic index carbs (and lesser amounts of carbs in general) is a no-brainer if you’ve read the first part of this article, even if it is not completely clear why- low (or lower) carb diets work. The ‘eat fat’ recommendation may shock a few people though; we want to loose fat so you are telling me to eat more of it???? The answer, you might have guessed, is yes, we do need to eat more fat to loose fat. Before we go on, a very important point must be stressed- if you want to loose weight you need to eat a lower calorie diet! If this condition is not satisfied a higher fat intake will actually cause an increase in body fat, rather than a loss in body fat. (Damn! And I thought this was the magic solution to loosing weight while eating whatever the hell you wanted…). We also need to be careful about what types of fats we add to the diet- we want the fat that we consume to help our weight loss efforts rather than hinder them. Stay away from saturated fat; this tends to decrease insulin sensitivity even while on a low calorie diet. As a side note, there are many ‘diet gurus’ out there who would argue that the fat source does not matter- I do not totally agree with this statement, and your cardiologist would tend to have the same view.
With saturated fats out of the picture we are left with the unsaturated fats and mono-unsaturated fats, some of which actually NEED to be in the diet, called Essential Fatty Acids (EFA’s). Without getting too much into the biochemistry of all these fats, EFA’s are unsaturated in nature and actually act to increase insulin sensitivity. Simply replacing a proportion of carbs in your diet with EFA’s will cause fat loss at the same calorie level! An excellent source of EFA’s are walnuts and flax seed oil; fish oil also tends to have benefits above and beyond that of some of the other EFA’s. Fatty fish such as Salmon additionally provides an excellent source of EFA’s. Olive oil is the most common example of a ‘monounsaturated fat’, although it is not essential. It is a good idea to include some monounsaturated fats in the diet, however, because the monounsaturated fats in olive oil tend to promote a healthy heart and blood vessels.
I can go on and on about the benefits of EFA’s, but the take-home message is that you need them for a number of health-reasons and an increased EFA intake at the expense of carbohydrate on a low(er) calorie diet will promote fat loss and build muscle making you leaner and more muscular. Additionally, the presence of fat in the stomach slows gastric emptying (i.e. how rapidly food passed from the stomach during digestion). This also actually reduces how rapidly carbohydrates are digested; essentially making the carbs we have eaten ‘lower-glycemic’. A lower glycemic carb raises blood glucose much more slowly, reduces insulin secretion, and reduces the likelihood that calories will be stored as body fat. A diet which has a moderate amount of fat from healthy sources in addition to low-glycemic carbohydrate and an adequate amount of protein is not only easier to follow because you are much less hungry even at a reduced calorie intake, but results in terms of fat loss seem to come quicker, most likely because the lower carbohydrate intake causes an overall lowering of insulin secretion.
While high carbs work well for some, the rest of us would do much better with much less. Give this type of diet a try; just remember that calories count; any book that tells you they don’t is not worth reading. Also note that my recommendations are similar to that of the popular ‘South Beach Diet’, or “The Zone” diet by Dr. Barry Sears. The Zone initially popularized the benefits of a lower carb/moderate fat diet, while the South Beach Diet is simply a modern version with a few details thrown in. Naturally, most of these books are touting some new and amazing approach to dieting, but the common way in which these diets work hinges on reducing insulin secretion by eating less carbs overall and choosing low-glycemic carb sources. Whether my generic description of this approach is sufficient, or you need a more rigidly defined diet such as “The Zone”, give the lower-carb approach a try; you will not be disappointed.