Hunger and satiety are two important mechanisms involved in body weight regulation. Even though humans can regulate food intake by will, there are systems within the central nervous system (CNS) that regulate food intake and energy expenditure. This complex network, whose control center is spread over different brain areas, receives information from adipose tissue, the gastrointestinal tract (GIT), and from blood and peripheral sensory receptors. The actions of the brain's hunger/satiety centers are influenced by nutrients, hormones and other signaling molecules. Ketone bodies are the major source of energy in the periods of fasting and/or carbohydrate shortage and might play a role in food intake control.
The point of keto is to force your body to deplete its glucose (and the stored form, glycogen) so it will have to use body fat as a fuel source. It’s capable of making ketone bodies from your fat, which can replace glucose as an energy-storing molecule if necessary. To do that, you have to break apart fat molecules thus ‘burning’ the fat off. But here’s the thing: your body really really doesn’t want to run out of glucose. No glucose means starvation as far as it’s concerned—even if you're not feeling hungry, your body is still missing one of its key macronutrients. And when you’re (nutritionally) starving, your body will start to break down protein just to get those sweet, sweet carbs. Of course, you have a source of protein in your body already: your own muscles. “When in starvation mode, your body breaks down muscle in your body,” says Giancoli. “Ketosis is a way of trying to preserve that protein. It’s not ideal, but it’s your body’s way of saving you.”
Because every person's metabolism is different, the sticks turn different shades of purple or pink for different people. And, yes, results vary depending upon the time of the day, whether or not you exercise and what you last ate. It doesn't matter whether your strips turn a dark or light color. Some people never even get into ketosis, but still lose weight easily. So don't worry about the exact level of ketosis shown on your test strips; what is more important is how your clothes are fitting, what the scale says and how you feel.
There are three instances where there’s research to back up a ketogenic diet, including to help control type 2 diabetes, as part of epilepsy treatment, or for weight loss, says Mattinson. “In terms of diabetes, there is some promising research showing that the ketogenic diet may improve glycemic control. It may cause a reduction in A1C — a key test for diabetes that measures a person’s average blood sugar control over two to three months — something that may help you reduce medication use,” she says.