Fat and Exercise

So I know it's been a long time since I've updated this, and I apologize for that but I've been crazy busy. At any rate, hopefully this is thought provoking to some and I can get some feedback, read on :-).

Most people I know that exercise regularly do so to for a number of reasons: to lose body fat, recompose their body, stay in shape, increase strength or some combination of all of the above. I am going to focus on the lose weight crowd today.

The dogma is that if we exercise more and watch our eating we will lose weight, specifically fat, and improve out body composition. In fact, the ACSM recommends exercise of 150 minutes a week will improve body composition over the long haul in combination with a healthy diet. However, what most anectodal evidence and clinical trials of implementing exercise in previously untrained peoeple along with giving nutritional guidelines result in marginal to little body fat loss. On the flip side, people who are educated on nutrition and eat properly, tend to lose body fat independent of exercise or not. That is, they lose weight and body fat regardless if they exercise or not. The amount of weight lost is about the same, the body fat difers (in favor of the exercisers typically), but the important part of the equation is the ability to keep this up for life and it seems as though the exercisers have an edge here. So where does exercise fit into this whole deal? Well let's get back to that in a moment, while first addressing another quandry.

What is obesity? Or in less dramatic terms, what is the definition of carrying extra unwanted fat tissue around? The powers at large will say that having extra fat or being obese is the result of not eating right (eating too much) or exercising too little. So a decrease in eating (amount) and increasing activity should work to rid the nation of this obesity epidemic. As it turns out, even though we (as a nation) are trying to become modestly more active and advised to eat more and more healthy, we are becoming more fat. Is this just a case of us being lazy and gluttons? I truly do not believe that people will continually eat themselves into submission, nor decrease activity on purpose to a level that makes them gain weight. What if it's all a byproduct of this two pronged attack on obesity (the advice to eat less and exercise more)? And moreover, what if obesity and less dramatic cases (such as having a few lbs to lose) are merely the accumulation of fat in fat stores? If we take that simple definition, then we would want to decrease the amount of fat in fat stores to lose the pounds. What regulates this and is exercise involved in that anyway?

When we exercise, we create a hormonal status withint the body that signals various pathways that we need to feed. This was referred to as "working up an appetite". Remember that? That phrase has seemed to disappear. To show this, a few studies I have came across indicate that people who were in an exercise group (who previously weren't) tended to eat more food than those who didn't exercse. In fact, the people tended to eat only as much more food as they needed to to make up for any extra activity. In lay terms, if someone burned a total of 2,300 calories throughout the day (by way of previous nutritional intake's effect on hormones, activity, cellular metabolism, environment, etc) then they would only willingly eat 2,300 or so calories a day. If this person wanted to lose weight, the establishment would say cut your calories down to 1800 or so and maintain the same or more activity level. Here's the rub, subconciously, that person will be less active overall or be active at a lower intensity to make up for the difference. Weight loss over the long term (6 months plus) will be small because the body is trying to maintain its set point. The set point got lower by changing the intake level of the person, and if the person ever varies from this calorie restricted diet, then the person will gain more weight, regardless of activity (since the hormonal status is already at a temporary set point and will only reset itself once the intake and output changes results in a change in size-better or worse).

Now there is noone out there who can tell you their exact intake down to 100 calories per day (accurately), nor is there a person who knows their exact output withing 100 calories of energy a day either. Think about it, was that 1 cup of brocolli, or 1.1 cups. Was it 6 ounces of chicken, or was their some marinade on the scale as well. Easily, throughout the course of a day that could result in well over a 100 calorie discrepancy. Also, did you take 15 steps to the door, or was it 14, and was it faster or slower than usual. And further, did your heart rate go up 7 beats a minute, or 6 during that walk? Again, this could cause a miscalculation over a day. So with all this uncertainty on input and output and because the dogma is that if the difference between calories in and calories out equals weight loss why do we almost always stay around the same weight (within 5 lbs) regardless of our diligence? How do we decrease the fat accumulation so we can decrease the fat stores with all this variance? It all boils down to hormones and maybe exercise :-).

Many hormones in our body (specifically testosterone, estrogen, growth hormone, insulin, glucagon, cortisol, etc) are involved in regulating fat metabolism (storage and breakdown). Insulin is the chief regulator of fat accumulation (lipogenesis) and in it's relative absence we see fat break down and be released into the blood stream as free fatty acids to be burnt as fuel (lipogenolysis and fatty acid oxidation). The sex steroids (testosterone and estrogen), growth hormone, and glucagon are all involved as well. Glucagon levels are elevated (relatively) when insulin is lower (again, relatively-not absolutely lower in overall values, that means that the overall value of insulin might be higher-3 units/milliliter of blood versus 1 unit/ milliliter of blood for glucagon). Testosterone works to increase protein synthesis (muscle rebuilding, cell turnover, and increased metabolism) only when insulin levels aren't elevated and growth hormone kicks off the whole cocktail only when insulin is low as well. These hormones work in unison while insulin is off on holiday to break down fat stores to be burnt as fuel and excreted in the urine/breath as ketone bodies. It makes sense that if we can consistently achieve a net flow of fat out of the fat stores, then we will lose body fat. So if we consistently have low or lower (relatively) insulin levels we will lose body fat because all of our other hormones are signalling the fat stores to unleash the beast (fatty acids) to be used as fuel. What's even more interesting is that without a decent amount of insulin (relative to the individual) we will not store fat either. That's right, without insulin to signal the accumulation of free fatty acids from the blood stream to be transported into the fat stores for storage as triglycerides we won't store fat. Higher than baseline levels of insulin are needed to store fat (specifically to activate an enzyme that transports free fatty acids from the blood to the fat stores and turns them into triglycerides). Think of triglycerides as statues in the body, they are hard to move around and even harder to break down and use for other useful purposes. Insulin wants to keep the existing statues where they are (inside the "house"-fat stores) and build new statues as well. The other hormones want to break down the statues into rocks to use for other purposes, as well as keep the rocks that aren't yet statues from being made into statues and keep them floating around for other uses. So if we could do one thing to help jumpstart the net movement of fat out of stores and into the bloodstream for use we would try to drop our insulin levels. How do we do this and dear God will someone tell me how exercise is involved in all of this?

Okay so a brief rundown of how insulin is increased in the body. When you eat, you produce a little insulin from your pancreas to help in absorbtion of the nutrients. The tricky part is how much and for how long does this insulin keep flowing. Meals consisiting of mostly starch (carbs) or sugars (carbs) will spike insulin sky high and keep it there a long time (depending on the size of the meal and your pancreas' status at the time). A meal rich in green veggies, fats, and protein will do just about nil for your insulin release, that is it will be small unless there is a sugary topping (like BBQ sauce) involved or a bread roll. I could go on for hours, but here's the gist, carbs- especially starch, sugar, and the like spike insulin sky high and for a prolonged period of time, and proteins, fats, and fiber don't do much. So without spiking our insulin throughout the day, we could keep it low and keep the body fat melting off. Good stuff. Now what about exercise, and the whole point of this post? Here goes...

So rememeber that the net flow of fat out of the stores results in free fatty acids being available for burning. Muscle cells use these, as do brain and nerve cells (preferentially), as well as other cells within the body. Now if these free fatty acids don't have a place to go to be burnt, they have the opportunity to be re-transported to the fat stores and rebuilt as statues (triglycerides). Here is why I wrote this whole thing. Do people exercise because they want to lose fat or do they exercise because they have all of these free fatty acids floating around that need to be used/expelled? Sounds kinda funny at first but check this; what if the presence of a bunch of free fatty acids in the bloodstream prompted various pathways to become active to increase activity at some level? This makes sense because typically the most fit folks have very low insulin in the blood and thus would have a bunch of free fatty acids at any given time, encouraging them to be more active and exercise (even if it's not necessarily formal exercise that's in a gym). Kind of an interesting theory, although I'm sure I'm not the first to come up with it. So what comes first, the fat or the exercise?