Several studies have demonstrated that the intake of sugar can decrease the activity of orexin cells, which is probably why we want to nap after a carb heavy lunch. This phenomenon also begins to explain the downward spiral of obesity triggered by our warped modern diet. Because we eat lots of refined sugars, washing down Twinkies with cans of Coke, we continually reduce levels of orexin in the brain, which then reduces levels of physical activity. In other words, we get fat and sleepy simultaneously
These experiments also document, at a biochemical level, why the modern American diet is such a catastrophic mess. The typical supermarket is filled with processed foods where the only relevant “nutrient” is some form of sweetener. (So-called “added sugars” – they are injected into food during manufacturing – now account for 16 percent of total caloric consumption. That’s 21.4 teaspoons of sugar and corn syrup every day.) While such snacks are unfailingly cheap and tasty, they also lead to sudden spikes in blood sugar and a reduction in orexin activity. We eat them for the energy boost, but the empty calories in these foods make us tired and sad instead. (There’s some suggestiveevidence that chronically low levels of orexin can increase the likelihood of depression.) And so we keep on swilling glucose, searching for a pick-me-up in all the wrong places.
consuming foods high in protein can increase the activity of orexin neurons. This, in turn, leads to increased wakefullness and bodily activity, helping us burn off the calories we just consumed. Furthermore, eating protein in conjunction with glucose – adding almonds to Frosted Flakes, in other words – can inhibit the inhibitory effects of sugar on orexin. The sweetness no longer makes us tired.
It should be noted, that sugar consumption is never a good thing, whether it is consumed with protein or not. Unlike glucose, which is rapidly absorbed into the bloodstream and taken up by the cells, fructose is shunted directly to the liver where it is converted to fat. Excess fructose consumption causes a condition called non-alcoholic fatty liver disease (NAFLD), which is directly linked to both diabetes and obesity.