Inclusion Criteria:  Healthy (see exclusion criteria) 25-65 years old Ability to travel to and from University of Bath campus  Exclusion Criteria:  Current or recent use (within the last three months) of weight loss drugs, medication that would interfere with study outcomes, sunbeds, or dietary vitamin D supplementation Change in weight of more than 5% in the last six months, or a significant change in lifestyle in the last two months Positive responses to the Physical Activity Readiness Questionnaire (PAR-Q) Presence of coronary heart disease, chronic kidney disease, type 2 diabetes, stroke, heart failure, peripheral arterial disease, severe hypertension (blood pressure >180/110 mmHg) BMI <18kg/m2 or BMI >40kg/m2