Certain fatty acids including omega-3 and omega-6 fatty acids impact regulatory functions in the brain.In short, omega-6 fatty acids promote obesity and omega-3 fatty acids against it.
The difference lies in the fact that the omega-6 fatty acid,arachidonic acid can be converted into lipid signaling molecules called endocannabinoids. The endoccanabinoid system responds to endogenous cannabinoids, called endoccanabinoids (Ecs) and the receptors they can bind to and activate.
It is named after the herbal drug cannabis which is a strong activator of this system.

The endoccanavinoid system is a complex signaling system that affects many functions in the body.

It is activate:

To relax: Reduction of pain and body temperature
To rest: Reduction of physical activity.
To habituate: Changes memory ability, increase addiction.
To protect: Reduction of neuronal activity.
To eat: Induction of eating, increasing fat deposits and boosting of the mental reward system.

Obesity and its health consequences are associated with a dysregulated endoccanabinoid signaling system that is chronically activated. Endoccanabinoids are good at helping to relax and calm down after stress and fear.
But if this system is chronically activated, it will influence our behavour towards resting, eating more and gaining weight.
Increased intake of fatty acids of the omega-3 family positevely influences the ration of omega-3 to omega-6 in blood and organs. In this way, less of arachidonic acid is incorporated into phopholipids, possibly resulting in decreased conversion of arachidonic acid to endoccanabinoids. Thus, dietary fatty acids can be a means to change the body’s fatty acid composition and thereby EC levels, ultimately affecting membrane signaling events and leading to changed energy metabolism (food intake and energy processing).

Ω Krill oil reduces plasma endoccanabinoids:

A number of studies have shown that krill oil may be beneficial in the treatment of metabolic disorders. Researchers found that the addition of krill oil to the diets improved several metabolic disturbances and reduced endoccanabinoids levels.

In a human study, in which 2 g of krill oil was given for four weeks and the blood levels of endoccancabinoids were measured. The results confirmed data in the literature describing increased levels of endoccanabinoids in overwight and obese persons with respect to normal weight subjects.
Ω krill oil but not menhaden oil or olive oil, was able to significantly decrease an endoccanabinoid called 2-AG in obese subjects that correlated with a decreased plasma phospholipid omega-6/omega-3 ratio. For the first time in humans, these data show that relatively low doses of omega-3 fatty acids like Ω krill oil can signifficantly decrease plasma 2-AG levels in obese subjects and looks to be a promishing approach to counter-act elevated endoccanabinoid levels.
By changing the balance between omega-6 and omega-3 fatty acids and reducing endoccanabinoid precursor availabilities, Ω krill oil may reduce the activity of the overactivated endoccanabinoid system in obesity and could potentially reduce the habit to eat.

It stands to reason that lowered visceral fat and decreased triglyceride levels in liver and heart would considerably lower the health risks associated with obesity.

Activates fat burning:

The omega-3 fatty acids in Ω krill oil have the ability to act as regulators of gene expression by affecting the activity of transcription factors. Research looking at the effect of fish oil and krill oil on gene expression and metabolic pathways in liver found that krill oil significantly increased the level of gene expression and metabolic pathways when compared with fish oil.The researches found that krill oil had a greater effect on gene expression than fish oil, krill oil increased gene expression in 4.892 genes, whereas omega-3 from fish oil only increased in 192 genes.
In fact there were 52 metabolic pathways that were signifficantly changed by krill oil with only four changed by fish oil and all four of these pathways were also affected by krill oil.
The researchers stated that krill oil was more bioactive than fish oil in terms of gene expression within the liver. In particular krill oil improved gene expression in a way that suggested improved glycose, fatty acid, lipid and cholesterol metabolism and increased energy production by mitochondria.

Reduces key enzymes in hepatic lipogenesis:

Lipogenesis is the process that converts carbohydrates or proteins to fat.
Reduction of tricarboxylate carrier (CIC). Transport carrier in the mitochondria that supplies carbon units to the cytosol needed for the generation of fat.

* Reduction of acetyl-CoA carboxylase (ACC). First enzyme involved in fatty acid synthesis.

* Reduction of fatty acid synthetase (FAS). A complex multifunctional enzyme needed for fatty acid synthesis.

* Liver problems,like fatty liver is a common problem among obese people and Ω krill oil supplementation could provide an efficiency way of decreasing liver lipid levels.