Hunger or increased feeling of appetite is often a big hurdle in weight loss. In this regard, ketogenic diet has become a popular way to lose weight over the recent years, partially due to the satiety that it can provide. In fact, various research studies have shed light on ketogenic diet’s potential to suppress appetite.
What are hunger hormones?
Appetite-suppressing effects of ketogenic diet can be largely explained by the diet’s influence on the hunger hormones. Among others, two of the hormones that influence our perception of hunger are ghrelin and leptin. While ghrelin is an appetite-stimulating hormone, leptin is an appetite-inhibiting hormone, also known as “satiety hormone.” They each signal the brain to regulate energy balance of the body. Abnormal levels of these hormones may contribute to development of eating disorders or obesity.
Ketosis may be the explanation behind appetite suppression.
Many studies agree that this decrease in feelings of hunger during ketogenic diet is linked to the state of ketosis. The state of ketosis is achieved upon reduction of carbohydrate as an energy source. In this carbohydrate-depleted phase, free fatty acids are broken down (a.k.a. fatty acid oxidation) into ketone bodies – βeta-hydroxybutyrate (BHB), acetone, and acetoacetate – to be used as the body’s fuel. Therefore, an increase in levels of these ketone bodies is a key indication of whether the body is in ketosis.
Studies show that during ketosis, secretion of the appetite-stimulating hormone, ghrelin, is suppressed in contrast to other forms of diets, which often is accompanied by an in increase in ghrelin levels. In fact, a study (Roekenes & Martins, 2021) showed not only the negative association between BHB and ghrelin concentrations during ketosis but also a positive correlation between concentration of BHB and that of other post-meal satiety hormones, namely GLP-1 and CCK. Another study (Nymo et al., 2017) done in London showed that upon refeeding of carbohydrates, reported feelings of hunger and levels of ghrelin increased back above the baseline as participants exited out of ketosis.
One study (Stubbs et al., 2018) assessed the effects of exogenous ketone ester (a ketone supplement) on appetite. This research compared individuals who were given ketone ester, containing the ketone body BHB, and those who were given isocaloric dextrose, a form of synthetic sugar chemically identical to glucose. It reported that compared with the group given dextrose, the group that was given ketone ester showed lower ghrelin levels with increased BHB levels after 1 hour. This corresponded with oral reports of reduction in both hunger and appetite after 1.5 hours.
Ketogenic diet’s potential ability to suppress the appetite may have widespread clinical implications for metabolic diseases that require a long-term weight loss as part of an effective treatment, such as type 2 diabetes. The exact mechanism of how and why is not yet clear, warranting future studies and clinical trials that test the safety and long-term applicability of ketogenic diet’s appetite-suppressing effects.