Some studies suggest that krill oil might have some protective effects against weight gain in high-fat diets.Yang, G., Lee, J., Lee, S., Kwak, D., Choe, W., Kang, I., Kim, S. S., & Ha, J. (2016). Krill Oil Supplementation Improves Dyslipidemia and Lowers Body Weight in Mice Fed a High-Fat Diet Through Activation of AMP-Activated Protein Kinase. Journal of Medicinal Food, 19(12), 1120–1129. While this was studied in mice, it provides some insight. Since krill oil’s omega-3 content helps to lower triglycerides, it’s less likely to cause weight gain when eating more fatty foods since the fat doesn’t stick around as long. Essentially, it probably won’t help you lose weight, but it can help balance your body against future dietary decisions.