Hack Your Metabolism, Part III: Sending the Right Messages

Note: this post is part three of a three part series. If you like it, consider contributing to a fundraiser called the Tour de Cure. If this helps you or someone you love, please consider clicking here to see more and donate to support my campaign on behalf of the American Diabetes Association. Thank you!

In the first part of my "Hack Your Metabolism" series, I talked about mindful eating and in the second installment I talked about what role exercise plays in regulating blood glucose and, ultimately, in losing or maintaining body weight.

In this final segment of the Hack Your Metabolism series, I want to talk about something that the two other discussion have in common. In my experience it is not obvious to most people, nor even to experts. And so it is the closet thing to "a secret" if not the secret behind making metabolic changes that improve your health in a measurable way. Including controlling body weight.

Here it is: mindful eating and the kind of exercise "dosing" I discussed both trigger long-term changes to the messages your body sends to regulate your metabolism. Insulin signaling is one of these types of messages, and an important one, for regulating the way your body uses energy.  What's counterintuitive about this is that we don't often think about changing eating habits or doing exercise as anything but direct interventions. That is, we think: eat less, gain less weight! Exercise more, burn more calories!

But our bodies are more complicated than that. And they are really, really good at adapting to external conditions that effect the most fundamental functions: eating, drinking, breathing, etc. It's that homeostasis thing again.

What I'm arguing here is that we should think of changes in our eating habits as a way to re-wire the circuits and change the messaging patterns that resulted in an increase in health risk. And we should adjust our expectations to how (and how long it takes for) the changes to take effect accordingly. This is a bit tough to get, I know. It took me a long while. So let's think through the example that most people care about a lot: losing weight.

Losing Weight: The Secret Is, There Is No Secret...Right?
On the surface it is simple. To lose weight you have to use more energy than you take in over some period of time. Right? Well...yes. Kind of. Not always, and not exactly.

Dieting - as an intervention in eating habits - is the most common way people pursue weight loss. But as my mindful eating post hopefully made clear, not all food is treated the same way in the body and the processes that signal your body to break down fat to use for energy may not happen if you eat too little of something (like carbs) or only something else (like proteins). So the first thing to ask when you are considering whether a new way of eating is appropriate as an intervention for you is to ask: what kinds of messages am I trying to re-program by eating in this new way?

Let's talk Paleo for a second. It may be the current hot diet. As with others, it is shrouded in controversy. And as with others, it has some elements that have been shown to work. In particular, it has been shown in at least one small-N study to improve insulin tolerance (though not a rate much different than doing those short, quick bursts of exercise I wrote about in part II). That same study showed that, over 12 weeks, it had no effect on weight loss or waist size, however.

All of this makes perfect sense to me. Why? Because the change in eating habits implied by the Paleo diet would have the most immediate impact on messaging related to blood sugar. Why? Less dietary carbohydrates means that the body would need to get better at using the blood glucose available and would initiate some changes to do this. This may or may not include a metabolic state called "ketosis," a condition that is sometimes portrayed as a desirable end goal for folks on the Paleo diet. But ketosis is not best understood as an end state. It is, rather, an indication of both the metabolic functions and messaging going on in the body. Specifically, it refers to the presence of elevated levels of ketone bodies in the bloodstream, something that happens when liver glycogen stores (remember those? the bodies' mid-term storage medium for blood glucose) are depleted.

Endurance athletes are familiar with ketosis, even if they don't know it by name. We have to train our bodies to switch to a different form of fuel during long efforts (lasting more than 45 minutes). And the better trained we are, the smoother this transition goes so that it is easier to maintain a given level of intensity even after our more immediate sources of fuel - carbohydrates - are depleted.

I bring up endurance athletes because this is a group that explicitly understands their exercise and eating habits to be in the service of causing specific kinds of metabolic changes: those that increase athletic performance in their sport. They (ok, we) can get a bit obsessive about it, in fact. And so in this group we have some interesting examples of what happens over time when we induce something like ketosis. I'll give you the short answer: the body can adapt. Even in extreme conditions, human bodies can learn to use other forms of fuel - in the case of Paleo, fat and proteins - to get what it needs. And, just as importantly, our bodies will continue to adapt to make these new processes more efficient. Eventually, we'll see a new set of metabolic rules in place that keep the body in a homeostatic state...all regulated by a new set of messaging pathways.

Habits Are What matter
The paleo diet isn't magic. And its efficacy in any one human body likely has little or nothing to do with the fact that some strain of ancient humans that you may or may not share ancestral DNA with ate in particular ways. If it works for you it is because it rewires your metabolism in a certain way, for a certain amount of time, to cause changes that reverse negative outcomes.

Your body adapts and changes constantly. It's trying to keep you alive and healthy, but it is rigorously biased to attend to immediate, basic needs. It will fulfill those needs in the short term to keep you alive at the expense of longer term health risks. So it is up to your conscious self to keep those longer term risks in check while complying with your greedy brain's need for fat.

The good news is that almost any sustained change in eating habits can cause signaling changes. So can almost any level of exercise. For how long? well that depends. And what changes does it cause? well that depends too. But what this all means is that there are no perfect diets and no perfect exercise routines. There are only habits that cause changes - harmful or helpful. And that word - habits - is important. One time doing anything is not likely to cause *any* signaling changes at all! So eat a piece of cake. Once. It's fine. Run once, if you feel like it, but it won't magically make you healthy.

What we are aiming for when we hack our metabolism are durable adaptations. These happen when we apply a new level of adaptive stress, which is a fancy way to say "habits."

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