There are a lot of different ways of reducing food intakes in laboratory animals and in humans, with dozens of exogenous peptides and proteins having this effect.
However, most have undesirable or dangerous side effects at obesity fighting doses, so the use of several different proteins and peptides as a combination therapy is being explored. One of the possible pathways for treating obesity with drugs is the CB1 endocannabinoid receptor. It has shown some success in small animal trials but still needs to be explored further on its own and in combination with other drugs.
Here is the full scientific article if you wish to download it.
This paper explores the known hormone and signalling pathways involved in obesity, and how combination therapies might potentially be a way of safely targeting them. The authors conclude that a lot more work needs to be undertaken before any therapies can be safely developed.
The severe side effects of peptide and protein hormone therapies for obesity have made them a dead end for research for a long time. Because they interact both with the peripheral and central nervous systems and across a wide variety of tissues and receptors, most of the drugs cannot be used in the quantities needed to exert an anti-obesity effect without having unintended side effects elsewhere.
These can be very severe and are the reason that there are few, if any, effective anti-obesity drugs available. However, in combination, these drugs offer greater potential. With a combination of three different drugs targeting different areas involved in obesity; the metabolism, the gastrointestinal tract, and the central nervous system, for example; it is hoped that the less severe or absent side effects of lower concentrations can make using several drugs at once an effective therapy.
There is currently not enough data to show combination therapies as effective and safe. The sheer scale of the research required into the complex web of interactions suggests that it will be some time before safe and effective therapies that target the endocrine system are available.
The ECS is well known to be involved in food intake, with the effects of exogenous cannabinoids in cannabis being clear and established in the literature. Different cannabinoids exert different effects on appetite, these differences could be exploited. The relative safety of cannabinoid therapy makes it a promising avenue for anti-obesity drug therapy.
The sheer scale and complexity of the body’s endocrine system is currently beyond our grasp. There are rich layers of interactions, cascades, pathways, and reactions that are only partially elucidated. Because each hormone triggers a wide variety of processes in the body, the simple administration of an endocrine protein or peptide for one specific target will necessarily produce a variety of effects.
It is hoped that by understanding the effects of each peptide and protein individually and in combination, effective appetite reducing drugs can be developed. However, there is a significant amount that needs to be understood before any therapy could be developed.
The human endocrine system is currently too complex and poorly understood to effectively target for appetite reducing therapies. There are tens of thousands of possible combinations and interactions that need to be understood before they can be exploited safely.