How Appetite Suppressants Work

The way that an appetite suppressant works might surprise you.

While appetite suppressants are sometimes described as ‘fat burners’, they in fact have a very different mechanism of action compared with a themogenic or even a fat blocker.

In fact, what many appetite suppressants are much more similar to, is an antidepressant!

The Role of Serotonin In Your Diet

Our hunger and satiety are both regulated by a number of different hormones which include most famously leptin and ghrelin. Leptin is the hormone that our stomach produces when we’re full, while ghrelin tells us that we’re hungry and we need to eat. While the stomach produces the neurotransmitters (the stomach is often called ‘the second brain’), it is the brain that receives them and this is then what leads to us going on midnight fridge raids.

Actually though, there are more hormones and neurotransmitters at play here. More specifically, when you consume carbohydrates and insulin is released, one of the few things that doesn’t get absorbed along with the other amino acids and nutrients, is tryptophan. Tryptophan is an amino acid that also happens to be a precursor to serotonin – which we know as the ‘feel good hormone’.

So when you eat and your body absorbs sugar and fat, the ratio of tryptophan in the bloodstream increases and you get that feeling of happiness and contentment that can only come from eating a kick-ass meal.

Conversely, when you have low serotonin, your brain suspects that hunger might be one reason and so ghrelin increases – leading you to go out looking for snacks.

This is why we ‘comfort eat’ and it’s why it’s so easy to end up with an unhealthy emotional relationship with our food.

How Appetite Suppressants Work

As such, many appetite suppressants actually contain serotonin-boosting ingredients. Tryptophan is unfortunately a banned substance in supplements (owing entirely to a misunderstanding that has yet to be fixed) but you can still find supplements that contain 5-HTP or ‘5 Hydroxy-tryptophan’. This can likewise be converted into serotonin in the brain and can provide a feeling of satiety.

What does this have to do with antidepressants? Well actually, many antidepressants work principally by preventing the ‘reuptake’ of serotonin, especially the well-known SSRIs (selective-serotonin reuptake inhibitors).

Not all appetite suppressants work this way mind. Others such as hoodia work by tricking the brain into thinking it has had glucose – affecting the hypothalamus directly to produce ghrelin.

Others still actually work by increasing the release of stress hormones. Not cortisol – which is actually a hormone closely associated with snacking – but rather norepinephrine. Norepinephrine increases focus and is one of the ‘fight or flight’ hormones. The reason this is good news is that when we are highly anxious or focussed on a task, we don’t pay as much attention to our diet. This is why some other medications – such as the anti-narcolepsy drug modafinil – can also lead to weight loss.

Appetite suppressants can work then, but it’s important to recognize all the other factors that are involved in snacking behaviour. Apart from anything else, routine has a massive role to play and is something you need to address!