Very low energy diets (VLEDs) and ketogenic low carbohydrate diets (KLCDs) are two dietary strategies that have been associated with a suppression of appetite. However, the results of clinical trials investigating the effect of ketogenic diets on appetite are inconsistent.To evaluate quantitatively the effect of ketogenic diets on subjective appetite ratings we conducted a systematic literature search and meta-analysis of studies that assessed appetite with visual analogue scales before (in energy balance), and during (while in ketosis) adherence to a VLED or a KLCD. Individuals were less hungry and exhibited greater fullness / satiety whilst adhering to a VLED, and individuals adhering to a KLCD were less hungry and had a reduced desire to eat. While these absolute changes in appetite were small, they occurred within the context of energy restriction, which is known to increase appetite in obese people. Thus, the clinical benefit of a ketogenic diet is in preventing an increase in appetite, despite weight loss, although individuals may indeed feel slightly less hungry (or more full or satisfied). This, rather than the absence of hunger altogether, can help individuals to comply with a restriction of energy intake in order to achieve weight loss.