This study examined the effectiveness of the manual for obesity Perdere peso senza perdere la testa (Losing weight without losing your mind) used in form of guided self-help on 161 patients. Three levels of treatments were compared: (a) guided self-help treatment (GSH); (b) minimal guided self-help treatment (M-GSH); (c) control condition (CC). At the end of the treatment, a significant reduction in body weight was observed in GSH and M-GSH, but not in the CC. At six-month follow-up 32.7% of GSH subjects and 15.1% of M-GSH subjects were able to maintain at least a 5% weight loss. The findings show that GSH is more effective than M-GSH in determining a significant short-term reduction of body weight.