How you can train your metabolism

A metaphor for metabolic flexibility

I'm driving through Los Angeles and I'm annoyed. Not the conscious type of annoyed where I'm irritated by the driver in front of me, but the subconscious type of tingly where you unconsciously grind your teeth and stiffen your muscles.

I feel my back tense up and start to slide back and forth in my seat to relieve the pain. And damn it, now I have to pee too. I slide back and forth in my seat like an overzealous Chihuahua. In the last 15 minutes, I've only covered one kilometer. There's nothing I can do. I'm stuck in traffic and it's annoying.

45 minutes later, I leave LA and drive across the country. The freeway becomes clearer and for the first time I can actually max out the speed limit. I take a deep breath and relax. My back feels good. I had either imagined I had to pee or I had accidentally wet my pants. Since I'm not sitting in a puddle, I probably just needed to relax.

A week later, I'm in North Caroline. I've just arrived in a sleepy little town called Asheville where there's no real traffic anywhere. This is how I'm spending my year. Three months at a time in Santa Monica and three months at a time in Asheville. This story is a perfect metaphor for something called "metabolic flexibility."

Fuel for the ride

You have two primary sources of energy that you can burn: Carbohydrates and fat (more specifically glucose and fatty acids for the biochemistry nerds). Apart from that, you can also burn a few other energy sources like protein and ketones.

But your body doesn't like to use protein because it's an expensive fuel (it takes a lot of energy to burn protein) and because protein is impractical - your body would rather save it for the purpose of moving and lifting things. You can also burn ketones, but this is linked to being able to burn fat.

We must not forget alcohol. This provides energy (7 calories per gram, to be exact), but it uses up space in your metabolic machinery. It's a source of acetyl-CoA, which is the same endpoint as the breakdown of fat and sugar. Alcohol arrives faster at this step, which is why a lot of alcohol in your diet interferes with burning these other energy sources. When your metabolism sees a lot of acetyl-CoA coming up, it sees no need to continue burning fat or sugar. Alcohol makes your metabolism less flexible.

You can think of alcohol as an 8 axle truck, carbs as an SUV and fat as a mid-size car. Midsize cars are what you see most often on the road and in parking lots. It would be great if they could move more freely, but the trucks and SUVs are often in the way. In other words, you better be able to handle sugar and alcohol if fat burning is what you want.

What about protein and ketones? What are they in this analogy? Protein is versatile (it can enter into energy production at many steps besides acetyl-CoA) but it's costly and impractical. It's like a motorcycle, a bicycle, an Uber or one of those electric scooters. They can help you get through traffic, but they're a pain when it starts to rain.

Ketones are kind of like public transportation. If their mirrors are high and they're efficient, then the rest of the road is less congested.

Flexibility vs. congestion

Metabolic flexibility is the ability to quickly switch from one energy source to another based on the availability of energy suppliers and demands for energy. In the traffic analogy, metabolic flexibility gives you a green wave for 20 intersections and clear, wide highways.

Applied to food, this means you can eat a big bowl of cinnamon toast crunch in the morning and your metabolism will barely break a sweat (much like any active teenager). Metabolic flexibility means that you can eat nothing but eggs and bacon for breakfast while your metabolism continues to run optimally.

Being metabolically flexible means you can get through 2.5 hours of afternoon soccer practice with nothing but a single burnt egg for breakfast and an unpeeled grapefruit in a brown bag for lunch. A healthy, flexible metabolism should be able to cope with all these demands and more.

Metabolic inflexibility means that one or more metabolic energy pathways are impaired. It means that in a single weekend there is a parade, a truck convention, a Superbowl and a major construction site on the highway.

An inflexible metabolism is a metabolism that is fat, tired, irritable and hungry even though it is getting enough food and energy sources. It's a metabolic traffic jam at the level of your mitochondria - too much fuel trying to get into the mitochondria and not enough energy being pumped out of the mitochondria.

Why you don't want a fast metabolism

Instead, you want a flexible metabolism. You don't want Usain Bolt unless he can also jump hurdles, do a handstand and juggle flaming swords. A flexible metabolism is capable of multitasking. It is not only good at burning sugar, but also excellent at burning fat.

But how do you achieve a flexible metabolism? Before we can understand this, we first need to understand what causes metabolic inflexibility. Research in recent years has put us on the track of what is going on with metabolism. For many years we have used a top-down approach.

What is the top-down approach to metabolism?

The top-down approach is as follows:

• Macronutrients and caloric load have hormonal effects
• Too many carbohydrates lead to high levels of insulin (the same applies to too many calories and too much protein).
• Very high insulin levels over a long period of time cause the body to stop responding to insulin (insulin resistance).
• Chronically high cortisol levels can also cause insulin resistance (keyword stress).
• Insulin resistance means that fat and sugar can no longer enter the cells to be burned.
• Fat and sugar (triglycerides and glucose) end up staying in the blood, where they cause damage.

Sound familiar? However, there is also a bottom-up approach that we are beginning to understand.

What is the bottom-up approach to metabolism?

The bottom-up approach is as follows:

• Large amounts of energy from several large mixed meals arrive at the mitochondria all at once.
• The mitochondria work overtime without breaks and begin to see fluctuating nutrient resources.
• Large amounts of free radicals (primarily hydrogen peroxide) damage the mitochondrial membranes and cause changes in the DNA (acetylation, etc.).
• Depleted stores and reserves of cofactors and signaling molecules (NAD+, glutathione, carnitine), which are required for mitochondrial function, lead to a slowdown in energy production.
• The slowing of mitochondrial function, the damage to mitochondrial integrity and the excess precursors of energy production from fat, carbohydrates and alcohol cause an accumulation of fat and sugar metabolites.
• Acetyl-CoA from the excessive breakdown of fat blocks the burning of carbohydrates.
• Acetyl-CoA from the excessive breakdown of sugar blocks the burning of fats.
• Alcohol acetyl-CoA blocks the breakdown of fats and carbohydrates
• Cellular function begins to break down.
• As a result, the function of the insulin receptors is impaired.
• This leads to bottom-up insulin resistance. Blood sugar levels rise. Blood lipid levels (triglycerides) rise.
• Now there is also top-down insulin resistance.

You turn into a fat, tired, snoring, depressed, anxious person who starts crying when your partner gets his Ben & Jerry's in front of you.

Let's break it down...

These bullet points are handy, but let's not forget the context. When fat, sugar and alcohol are metabolized, their breakdown products approach acety-CoA. Protein is slightly different as it can enter the metabolic energy pathway at many different points.

Something you need to know about metabolism is that it is not good at multitasking when it comes to burning energy sources. It works most efficiently when one energy source dominates. One way to understand this biochemically is to recognize that one energy-producing pathway produces multiple signaling molecules that block the other pathway.

For example, when you burn fat, you produce many different compounds that suppress the key regulatory enzymes that drive the sugar-burning pathway (such as pyruvate, dehydrogenase PDH and phosphofructokinase PFK). And vice versa - when you burn sugar, you create molecules that block fat-burning pathways.

The pathways for burning fat and sugar inhibit each other, so the following scenarios can occur:

• If you eat more fat, then this blocks some of the regulatory steps in burning sugar.
• Eating more sugar blocks some of the regulatory steps involved in burning fat.
• If you eat large amounts of both in combination, then neither pathway will run as efficiently as it could.

Too much of one energy source can lead to insulin resistance. Eating too much sugar usually leads to a top-down effect where insulin kinetics end up being impaired - insulin resistance occurs and the entry of energy sources (fuel) into the cells slows down.

Excessive fat tends to lead to a bottom-up effect. The breakdown of fat generates a large amount of carbon. This overwhelms the mitochondria, leading to dysfunctional mitochondria (a change from interconnected to dispersed mitochondria) and inflexible mitochondria (a competitive inhibition of sugar-burning pathways).

This leads to reduced cellular energy production and increased levels of reactive oxygen molecules, which can have a negative impact on cellular protein production and function, including impaired insulin receptor sensitivity. This leads to insulin resistance and reduced entry of energy carriers into the cells.

The four-stage process of burning energy sources

This is the reason why the "hallmark" of metabolic derailment is "metabolic syndrome". This is a condition in which both fasting blood glucose levels and fasting blood lipid levels (triglycerides) are elevated.

The particularly disturbing aspect of this metabolic puzzle is that lipolysis (the breaking down of fat) and glycogenolysis (the breaking down of stored glucose) are still occurring - especially during times of stored need (e.g. exercise). However, the ability to burn these energy sources remains impaired, as the release of fat and sugar is one step in the four-step process of burning energy sources.

This process works as follows:

1. The energy source is released at the site where it is stored (in the case of fat, lipolysis - the release and breakdown of fat in fat stores).
2. The energy carrier is transported to where it is needed (blood flow is important here).
3. The energy carrier must reach the cells. This is where the insulin receptor comes into play.
4. The energy source is burned in the cell. In the case of fat, fatty acid oxidation is the process by which fat is burned in the mitochondria.

In the case of metabolic inflexibility, the defect occurs either in step 3 (top-down effect), step 4 (bottom-up effect) or both. Which is more important - top-down or bottom-up effect - is something that science is still working on. The whole thing is a complex story of interactions between genetics and environment. However, we know that both are involved, which gives us some great tools.

How can you fix a metabolic inflexibility?

Maybe you think all this is another way of describing people who overeat. You wouldn't even be wrong about this, but it might also explain why my friend, a 90 kilo bodybuilder, can consume 4000 kcal and stay lean, while another friend of mine, a 100 kilo recreational athlete, gets fat if he exceeds 2500 kcal per day.

Apart from that, we wouldn't even be having this discussion if people could follow the "eat less" recommendation. The fact is, they can't. And part of the reason for this is metabolic inflexibility. Not only does having an inflexible metabolism change the way we burn energy sources, it also causes us to crave more and eat more.

The lifestyle of our ancestors is a good starting point to understand the path back to a functional metabolism. Originally, we humans were hunter-gatherers:

• Sometimes we ate what we had gathered because the hunt was unsuccessful.
• Sometimes we only ate what we had hunted because the gathering was unsuccessful.
• And we certainly ate both sometimes.

We also ate fewer calories and lower amounts of fat and sugar. In addition to this, we probably had a greater separation between different macronutrient types. Fruit and tubers - our natural sources of sugar - were only available at certain times of the year, and we didn't have the tools to grow wheat and bake bread. Wild animals are not super fatty. And high-fat vegetables are only available at certain times of the year.

Combine this with a longer night's sleep (we went to bed when the sun went down and woke up when it rose) and a lot of walking and you'll realize why being metabolically flexible was a great survival advantage and a natural consequence of living in harmony with natural cycles.

A Paleolithic dinner, which was probably the largest and usually the only meal of the day, was not a matter of passing the corn, a brisket as a second course and cake for dessert. It was more a meal consisting solely of venison and a few dried raspberries.

Becoming metabolically flexible means that there are a few things we can do that were something completely natural to our ancestors.

Now that we know the problem, in part two we'll look at strategies you can use to solve it.

Source: https://www.t-nation.com/lean-built-eating/how-to-train-your-metabolism/

By Dr. Jade Teta