Inclusion Criteria:  Non-smoking Non-contraceptive using Competitive female endurance athletes 18-35 years of age training minimum 5 times a week Athletes with LEAF-Q score ≥ 8 and EDE-Q score < 2.5 from part 1 will be invited to participate in the 16 week FUEL intervention  Exclusion Criteria:  Pregnancy or planned pregnancy Risk of eating disorders defined as an EDE-Q score ≥ 2.5 chronic diseases (e.g. diabetes, crohn's disease, thyroid dysfunction) Use of any medication that may disturb hormonal balance