TVP_lab

We haven't received any criticisms from activists so far, and hopefully we won't in future! As scientists, we are not trying to push any public agendas, but simply to construct hypotheses and try to answer them in a scientific manner.

Another important point here is that the amount of fat in any given individual will not directly pose a risk of disease. There are some individuals that have a lot of fat, but as it is functioning properly, they are metabolically healthy! Conversely, there are some slim individuals with very little or no functional fat tissue that are very insulin resistant.

Sam from our group wrote a review a while ago titled 'It's Not How Fat You Are, It's What You Do with It That Counts'. We still think this statement holds true!

Link to review: http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0060237

Kasparas

Hey the realplanetX

This is a great question.

Fat cells have three major functions:

1. They store calories long term. A Kg of fat has more than twice the calories as a Kg of carbs or protein. This means if you need to cart around an energy store it is more efficient to use fat than other types of storage molecule.
2. Fat cells secrete loads of hormones that control different aspects of how our bodies work. For example, the hormone leptin is produced by fat cells. It tells the body if it has enough nutrients to do certain things, for example if you have really low leptin levels women temporarily cease being able to reproduce. This would have evolved to prevent animals getting pregnant when you lack enough fat reserves to support the pregnancy.
3. Fat cells buffer our daily lipids. After we eat insulin tells fat cells to take up the fat we have eaten and store it. We can then burn the carbohydrate parts of our meals. Then, when we are asleep the nervous system tells fat cells to break down and release it into the blood stream. These fatty acids that are released by adipose tissue can then be used by organs like muscle and heart for fuel.

In this article we focus on aspect 3 - fat cells as lipid buffers.

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Cheers,

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Sam

Hey Bokbreath,

There are several ways fat can be dysfunctional, but what we focus on in this paper is its daily role in controlling what the body does with the fat you eat.

Healthy fat (adipose tissue) takes up the fat we consume and stores it until it is needed for fuel, such as at night when we are asleep. When obese people eat a meal their adipose tissue does not take up the fat. Instead, the fat is directed into other organs, such as the liver and muscle where it causes insulin resistance.

Importantly, the adipose tissue of obese people is also bad at releasing fat when they are asleep, meaning that obese people have to use lots of glucose when they are sleeping to provide energy.

So fat that is dysfunctional is bad at both taking up and releasing fat, leading to the body using the wrong nutrients at the wrong time.

Sam Virtue

Hey coreyrenton,

This is an interesting idea. There are suggestions out there that yo-yo dieting (ie losing then gaining weight repeatedly) may be bad for you, but I hadn't thought about it impacting on adipose tissue depots differently.

We haven't done this personally, but I had a quick look at the literature there are a few studies out there suggesting weight loss and regain can affect body fat distribution. Some other studies suggest that this does not happen, so it seems that it is not currently clear.

However, if I understand what you are asking, when we lose weight we don't necessarily lose fat cells- the cells have a half-life of about 8 years. What happens is the cells shrink as they empty of fat. They can then refill.

Cheers,

Sam

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Hey Oyvas,

Absolutely- we are also working on that in the lab. One important point about making white fat browner (or beiger) is that it is not enough to just have bat, you need to be able to activate it (pharmacologically or with nerves) and provide it with fuel (with a good blood supply). Think about it as like putting a giant engine in a car. It won’t do much unless you connect the fuel supply and the accelerator peddle!

Sam Virtue