I watched a video recently, made by a “nutritionist”, who made the claim that “we all know that sugar just turns to fat”, so let’s explore that.....

This is a process known as de novo lipogenesis (and we will fully deal with it in the next lesson), which is the production of triacylglycerol (fat) from glucose. This rarely happens in humans, and is really of no major concern to us, since carbohydrates are primarily going to be used for energy or stored as glycogen, with the dietary fats being stored as excess body fat where necessary.

Basically, if you eat excess energy, it needs to be stored;

• If we have an excess of dietary fat, that can be very easily stored right away with little work.
• If dietary fat is low relative to your total intake, then the excess can be derived from its molecular components, which can come from carbohydrates, or protein.

If protein is excessive, it can be converted to glucose for storage via gluconeogenesis, or as mentioned, donate some of its components toward lipogenesis (fat synthesis).

This paper concluded that “only when carbohydrate (CHO) energy intake exceeds total energy expenditure (TEE) does de novo lipogenesis (DNL) in liver or adipose tissue contribute significantly to the whole-body energy economy. It is concluded that DNL is not the pathway of first resort for added dietary CHO, in humans. Under most dietary conditions, the two major macronutrient energy sources (CHO and fat) are therefore not interconvertible currencies; CHO and fat have independent, though interacting, economies and independent regulation.”

Therefore, whether we worry about sugar, or carbohydrates in general, we should be concerned with our total energy intake as the predictor of energy substrate use/storage. Fat is only synthesised from glucose, or stored (for good, leading to net fat gain) in an environment where we have a calorie surplus. A calorie surplus means that we eat more energy/calories than we require, therefore the excess energy is stored within the fuel stores of the body; intramuscular glycogen, liver glycogen and the blood will house carbohydrates, with dietary fat being stored as intramuscular lipids or as adipose tissue (body fat), which is split into subcutaneous and visceral adipose tissue. This process of storing excess energy occurs independent of whether the excess occurs from protein, carbohydrates or fat. And sugar falls within that carbohydrate bracket.

What we must remember is that it’s not just as simple as saying “this is protein”, “this is a carbohydrate”, “this is fat” when predicting what actually happens in the body. There is an extensive “metabolic map” that looks a bit like the London underground, with hundreds of different pathways overlapping, all of which offer different fates for substrate “x”. The ingested pro/carb/fat do not simply remain as they were when ingested, but rather meet their fate in response to the contextual environment to which they enter.

It’s the energy content (calories) that determines whether or not excess energy is stored (chronically), which occurs regardless of where the excess calories come from.

But there has to be a downside of sugar, right? Yes, there is. We do not want to promote a diet high in sugar. So let’s get back to our question.......

The full article is available in the Triage Militia, but hopefully that sheds some light on a very common question: "does sugar turn to fat?".

Kind Regards,

Gary & Paddy

Triage Method