Kisspeptin, appetite and anxiety

Hormonal activity was detectable. Hunger, food consumption and anxiety still had to be measured on their own terms.

The food-intake experiment

The food-intake experiment in women with overweight or obesity is unusually satisfying to think about. Intravenous kisspeptin increased LH, confirming biological activity, while self-rated hunger and objectively measured food intake were unchanged versus vehicle. The hormonal result gave the experiment a clear sign that the intervention was active even though the appetite outcomes stayed quiet.

Measuring both hunger and actual food consumption gives the appetite question a concrete form. In this population and experiment, neither changed. That is a useful boundary on the signal's observed reach, and it deserves to survive any retelling of the subject.

A meal, water glass and cutlery sit on a research-room table beside an olive chair. — An editorial still life suggesting a food-intake experiment; the meal does not reproduce the study menu.

The anxiety crossover trial

In the randomized crossover trial reported in 2025, 95 participants—63 men and 32 women—received kisspeptin-54 or placebo. LH increased robustly. State anxiety, cortisol, blood pressure and heart rate did not change significantly versus placebo.

These outcomes answer separate questions. The anxiety measurement concerns anxiety, the cortisol measurement concerns cortisol, and the cardiovascular observations concern the measures reported during the experiment. Flattening that list into a claim about feeling better would throw away its most interesting feature: the unchanged anxiety finding, especially beside work on sexual and emotional processing.

Acute observations

The anxiety trial's observations are reassuring about the measured responses under its experimental conditions. Predicting the consequences of prolonged exposure would ask more of these observations than they can give. The questions would change with the duration of observation, the population and the outcome being sought.

The fading LH response under repeated administration is a useful reminder of how much duration can matter, although it addresses a different question from the anxiety experiment. Both studies become more informative when their specific outcomes remain attached to them.

The ripple image becomes useful to me here. It permits a response to reach one measured endpoint while another remains unchanged. I think that selective reach is more interesting than the idea that a biologically active substance must improve everything nearby.