Yes there is, below you will find a couple of studies that you can follow up on:
Cochrane, Gordon; Friesen, J. (1986). Hypnotherapy in weight loss treatment. Journal of Consulting and Clinical Psychology, 54, 489-492.
Kirsch, Irving (1996). Hypnotic enhancement of cognitive-behavioral weight loss treatments–Another meta-reanalysis. Journal of Consulting and Clinical Psychology, 64 (3), 517-519.
Hypnosis as an adjunct to cognitive-behavioral psychotherapy for obesity: A meta-analytic reappraisal. by Allison, David B.; Faith, Myles S. Journal of Consulting & Clinical Psychology. 1996 Jun Vol 64(3) 513-516
Controlled trial of Hypnotherapy for weight loss in patients with obstructive sleep apnoea. Stradling J, Roberts D, Wilson A, Lovelock F., Int J Obes Relat Metab Disord. 1998 Mar;22(3):278-81.
Hypnosis as an adjunct to cognitive-behavioral psychotherapy for obesity: a meta-analytic reappraisal. Allison DB, Faith MS., J Consult Clin Psychol. 1996 Jun;64(3):513-6.
Hypnotic enhancement of cognitive-behavioral weight loss treatments: Another meta-reanalysis. by Kirsch, Irving, Journal of Consulting & Clinical Psychology. 1996 Jun Vol 64(3) 517-519