How is fructose and glucose different


Glucose and fructose are both sugars, but they are metabolized differently in the body, and they have distinct impacts on health and appetite.

  • Glucose is utilized by every cell on the planet for energy. It's so important that if you don't consume it, your body will produce it through gluconeogenesis. Glucose is necessary for brain function, heart health, and hormone production. It is a preferred source of fuel for the nervous system and is handled uniquely by the body. Glucose consumption triggers insulin release, promoting glycogen storage and regulating blood sugar levels 1.

  • Fructose, on the other hand, generally needs to be converted to glucose in the liver before it can be used. This conversion process can affect hormones linked to appetite suppression, potentially leading to increased hunger. Fructose activates the brain's reward center, like addictive substances such as cocaine or heroin, promoting a strong desire for consumption and can suppress the activity of hormones that would otherwise reduce hunger. Fructose can also increase levels of the hunger hormone ghrelin in your body, making you more prone to seeking out sugary and fatty foods 2 3.

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Additionally, while glucose activates the basal ganglia involved in movement and planning, fructose preferentially stimulates the nucleus accumbens, which is associated with reward 4. Consuming fructose shifts our hormone system and neural pathways in the brain, leading to increased hunger regardless of calorie intake 2.

Furthermore, fructose does not have a biochemical function in vertebrate life, unlike glucose, and there's no requirement for dietary fructose for any biochemical reaction. It is still widely present in the modern diet and is associated with increased fructose consumption, which can lead to various health issues 3.

Lastly, the idea of the glycemic index was also criticized and dismissed as inaccurate, implying that the way we look at sugars and their impact on blood sugar should be reconsidered 5.