I am almost 9 weeks post op....have lost almost 30 lbs and run 4x a week min 7 miles each run and am burning 1000 calories during each workout. I am literally not hungry, in fact I'm less hungry than I was a few weeks ago, so my appetite is disappearing! How can that be with the added exercise?

Best if you read this

The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review.

AuthorsKlok MD, et al. Show all Journal

Obes Rev. 2007 Jan;8(1):21-34.

Affiliation

Department of Endocrinology, VU University Medical Center, Amsterdam, the Netherlands.

Abstract

Leptin and ghrelin are two hormones that have been recognized to have a major influence on energy balance. Leptin is a mediator of long-term regulation of energy balance, suppressing food intake and thereby inducing weight loss. Ghrelin on the other hand is a fast-acting hormone, seemingly playing a role in meal initiation. As a growing number of people suffer from obesity, understanding the mechanisms by which various hormones and neurotransmitters have influence on energy balance has been a subject of intensive research. In obese subjects the circulating level of the anorexigenic hormone leptin is increased, whereas surprisingly, the level of the orexigenic hormone ghrelin is decreased. It is now established that obese patients are leptin-resistant. However, the manner in which both the leptin and ghrelin systems contribute to the development or maintenance of obesity is as yet not clear. The purpose of this review is to provide background information on the leptin and ghrelin hormones, their role in food intake and body weight in humans, and their mechanism of action. Possible abnormalities in the leptin and ghrelin systems that may contribute to the development of obesity will be mentioned. In addition, the potentials of leptin and ghrelin as drug targets will be discussed. Finally, the influence of the diet on leptin and ghrelin secretion and functioning will be described.

I cant word it any better than this for you