Why some people stay skinny and others get fat
What I want to put forward today is that there is evidence for two distinct modes of human metabolic state. One is being “fat adapted”. That is, a state where the hormone insulin is well controlled and the body is able to access its stores of fat as a primary source of fuel. This, I contend, is the normal human state. The complex interaction of cells, hormones, enzymes and much much more is in balance. We homeostatically maintain a desirable body weight by self-regulating inputs and outputs. In this state, if we over-eat, we will compensate and burn it off. And vice versa if we under-eat. The mechanisms are complex and not all are well understood. It’s at least a great starting hypothesis. Good science is needed to nail down the whole mechanism but putting together animal and human evidence points to this. This is fundamentally why the “calorie is a calorie” dogma that has plagued nutritional science for the past 40 years is wrong.
When you are “fat adapted” you can easily utilise fat, you have less craving for simple carbs and, most importantly, insulin is well controlled.
However, when you continually eat large amounts of carbohydrates, especially simple refined carbs, then the second mode of human metabolic state results and the body becomes what I have decided to term “metabolically dysregulated”. Others have used the term “metabolically deranged”, but I find that a little too emotional! The mechanism is simplified as follows:
- The body has to continually deal with large loads of dietary carbs.
- It does this by producing insulin, a storage hormone which shuts off the ability to burn fat as a fuel source and get carbs into cells. Some will go into muscle cells (especially in an active individual); some goes into the liver; but if the muscle cells and liver are full, which they often are because they have a limited capacity and people often expend very little energy, then the carbs are stored in fat cells. That’s the basic mechanism for the storing of fat. Insulin also drives extra fat into fat cells too. That’s it. Simple. Insulin makes fats cells get bigger. Without a rise in insulin, there is no easy mechanism for this process.
- Insulin also blocks an important hunger hormone called leptin. Leptin is secreted by fat cells and signals to the hypothalamus in the brain that the body is not starving. By blocking this hormone, insulin is effectively block the “off switch” for hunger so we over-eat.
- Insulin also down-regulates (the process by which a cell decreases the quantity of a cellular component) the pleasure hormone dopamine’s receptors in the brine. This is what gives simple carbs their addictive quality.
- Insulin also down-regulates sympathetic nervous system activity resulting in a reduced propensity to expend energy through both incidental and purposeful physical activity.
- It’s a downward spiral as you get fatter and less regulated and continue to bombard the body with large doses of dietary carbs. You become more and more insulin resistant, both at the muscle and liver cell level. In other words, you need more and more insulin to get the carbs into the cells. Insulin is permanently high. So your cells become more existent. You are always storing fat, never burning it and a state of hyperinsulemia (high insulin) ensues, even when you are not eating. You become fatter, especially around your central area (visceral obesity), which drives more inflammation and increased insulin resistance. Oh boy….!
- Eventually, the beta cells in the pancreas which produce insulin start to fail and you can’t manage your blood sugar levels at all. That’s Diabetes. Constantly high blood sugar is toxic to all parts of the body it touches, and it touches everything of course.
So that is what I call becoming metabolically dysregulated. It is caused by lots of simple dietary carbs. It’s a pandemic. It’s because we have a food supply choked full of processed carbs. And even worse, our medical advice is to go low fat. Low fat, by definition, will mean high carb for the body. More on why in later blogs.
So that’s the dietary choice you have in my view. Eat whole unprocessed foods; low carb, leafy vegetables, moderate protein, high fat and you will avoid the insulin peaks and eventual dysregulation described above. Eat the carbs, send insulin way up and suffer the consequences of metabolic dysregulation. Fat burning shuts down,energy out shuts down. Fat storage goes up. Because energy out is synonymous with quality of life, you feel crap. Being the best you can be has a central requirement of being metabolically well regulated. That’s why I am so interested in nutrition.
Thanks to Helen Kilding for her help with this blog