Krill oil supplementation may preserve muscle during weight loss, according to recent study

A recently published randomized placebo-controlled trial¹ examined the effect of krill oil on muscle retention during weight loss through alternate-day fasting (ADF). As noted in the introduction of the study, loss of muscle can possibly have negative effects on metabolic health. Additionally, it explains, some previous studies have suggested that long-chain n-3 polyunsaturated fatty acids (LCn-3 PUFA) supplementation can support fat loss and muscle retention, and krill oil is a source of LCn-3 PUFA. The study, “Benefits of Krill Oil Supplementation During Alternate-Day Fasting in Adults With Overweight and Obesity: A Randomized Trial,” was published in Obesity in July 2025. The krill oil used in the study was supplied by marine-based ingredient developer Aker BioMarine.

In this eight-week study, 41 participants, ages 25–65 with above average body mass index (BMI), consumed either four capsules of krill oil amounting to 4 g per day (containing 191 mg EPA, 94 mg DHA, 78 mg choline, and 100 mcg astaxanthin) or a vegetable oil placebo. EPA and DHA supplementation has been associated with reduced inflammatory markers, the study explained. Body mass, fat-free mass (FFM), and hand-grip strength were measured before and after the trial period.

Highlighted results include:

• FFM and hand grip strength were significantly reduced in the placebo group compared with the test group
• The reduction of TNF-α concentration (inflammatory markers) and plasma concentration was greater in the test group than in the placebo group
• EPA, DHA, and omega-3 index were all greater in the blood samples of the test group compared to placebo
• A greater reduction in systolic blood pressure was associated with the test group compared to placebo
• Body mass and fat mass were not affected by the krill oil

Ultimately, the researchers concluded that supplementation with krill oil decreased the loss of FFM and strength during weight loss. “While losing weight is often a good thing, one of the unintended consequences is that we don’t only lose fat, but we also lose muscle,” stated Stuart Gray, study co-author, in a July 17, 2025, press release². “In this study, we have found that krill oil can help to preserve our muscle mass and strength as we lose weight. As maintenance of muscle is very important for our overall health and quality of life, these are extremely exciting findings.”

The researchers suggested that future studies covering a longer duration of test period on krill oil during weight loss are needed to further show the impacts and mechanisms behind the supplementation.

“We are pleased to continue our work with the University of Glasgow to further explore krill oil and its positive effects on muscle mass and function,” stated Line Johnsen, senior vice president of human health ingredients research and development at Aker BioMarine. “We have previously conducted scientific studies with Dr. Gray and his team to show how the important nutrients found in krill impact muscle strength and mass with age, and this follow-up study helps strengthen our understanding of this area.”

References

1. Alblaji, M.; Gray, SR.; Almesbehi, T.; Morrison, DJ.; Malkova, D. Benefits of Krill Oil Supplementation During Alternate-Day Fasting in Adults With Overweight and Obesity: A Randomized Trial, Obesity, 2025. DOI: 10.1002/oby.24354.
2. Aker BioMarine. Krill oil supplementation helps preserve muscle strength and mass during diet-induced weight loss https://www.akerbiomarine.com/news/preserve-muscle-strength-and-mass-during-weight-loss?hsCtaAttrib=191242313294 (accessed 2025-07-18).