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Hunger sensation (HS) in humans physiologically shows intraday (circadian) and within-day (ultradian) recursivity. This intrinsic periodicity was investigated by applying the cosinor method and spectral analysis to the 24-hour profile of HS (orexigram) derived by a self-rating score (from 1 to 10 hunger units [HU]) recorded every half-hour. The study of circadian and ultradian recursivity on the orexigram was performed in 30 diabetic obese patients ([DOPs], 14 men and 16 women aged 22 to 62 years; body weight, 77 to 130 kg; body mass index, 31–47). The control group consisted of 30 clinically healthy subjects ([CHS], 15 men and 15 women aged 21 to 60 years; body weight, 65 to 72 kg; body mass index, 23 to 25). DOPs showed two types of orexigrams in which hunger was felt with limitation to the diurnal part of the day or with extension to the night, respectively. The type 1 orexigram was characterized by a normal spectrum and circadian rhythm. The type 2 orexigram was characterized by subsidiary ultradian components associated with an abnormal elevation of the circadian mesor and a significant delay of the circadian phase, as the spectral analysis was indicative of a structural difference in the frequencies that sustain the intraday and within-day recursivity of the HS. Accordingly, DOPs can be recognized by their orexigram as “eurectic” or “hyperrectic” to indicate subjects with a normal or an exaggerated HS, respectively, during the 24-hour span.

In human beings, hunger is a proprioceptive signal that shows intraday (circadian components) and within-day (ultradian components) recursivity. Both periodic components can be investigated by chronobiometric procedures by combining the Cosinor method with spectral analysis. A 24-hour profile of hunger sensation (HS) can be plotted on a 1-to-10 scale of intensity using self-rated scores performed every half-hour of the day. Circadian and ultradian components were studied in 60 patients affected by essential obesity (20 men and 40 women; mean age, 38.4 years; mean body weight, 101 kg) before and after treatment with dexfenfluramine (Isomeride®; Servier, Orleans, France) 15 mg orally twice daily, for 30 days. The control group consisted of 30 clinically healthy subjects (15 men and 15 women; mean age, 37.5 years; mean body weight, 69 kg). Chronobiometric analysis shows three patterns in obese patients, which suggests that HS may be normal (eurectic obesity), exaggerated (hyperrectic obesity), or diminished (hyporectic obesity). After dexfenfluramine administration, HS was showed a substantial decrease in the daily mean level. The spectrum of resolution in circadian and ultradian components was found to be maintained in eurectic obesity and partially readjusted in hyperrectic and hyporectic obesities. This demonstrates that dexfenfluramine acts not only as an anorectic but also as a chronizer by interfering with the recursive components of HS. The anorectic and chronizing effects suggest that dexfenfluramine is a “chronoanorectic drug” that interacts with the chronobiologic properties of the serotoninergic system.