Developing effective weight loss strategies for shift workers.

INTERVENTION: Diet 1: 5:2 Day fasting diet For five days of the week participants will eat their habitual diet, and on two days of the week (the two ‘fast’ days) they will be required to restrict their energy intake to 2100 kJ/day (female) or 2500 kj (male). These two days will correspond with days that incorporate a day shift. Participants will be provided with study food on each of the energy restriction days. Diet 2: 5:2 Night fasting diet For five days of the week participants will eat their usual diet, and on two days of the week (the two ‘fast’ days) they will be required to restrict their energy intake to approximately 2100 kJ/day (female) or 2500 kJ (male). These two days will correspond with days that incorporate a night shift. Participants will be provided with study food on each of the energy restriction days. Diet 3: 20% Continuous daily Energy Restriction (20% ER) Based on a participant’s habitual diet (recorded at baseline), usual intake of total energy (kJ) will be reduced by 20%. Participants will be provided with study meals on two days of the week so that the same level of support is provided to each of the three intervention groups. Each dietary strategy (5:2 Day; 5:2 Night; 20% CER) will be followed for 6 months. Dietitians will deliver the intervention to each individual in person. Following their baseline visit, participants will meet with a dietitian in person every 2 weeks for the first two months (4 visits), and then monthly (4 visits). Following the intervention period, there will be a 12 month maintenance phase during which time participants will be monitored. During the 12 month maintenance phase, participants will receive a phone call from a study dietitian one month into the maintenance phase, and then meet the study dietitian in person at 2 months, 6 months and then at 12 months. Adherence to dietary interventions will be monitored and assessed through a combination of food diaries, 24 hr diet recalls and c CONDITION: Diet and Nutrition ‐ Obesity Metabolic and Endocrine ‐ Metabolic disorders Obesity;Metabolic Syndrome; ; Obesity ; Metabolic Syndrome PRIMARY OUTCOME: Body weight in kg will be assessed using scales; [0, 3, 6, 12 and 18 months (0 and 6 months primary time points for hypothesis testing); ; ] HOMA‐IR; Fasting glucose (clinical chemistry analyser) and fasting insulin (ELIZA); [0, 6 months] SECONDARY OUTCOME: Anxiety scale measured by the DASS‐21 questionnaire[0, 6 and 18 months post enrolment] Blood pressure will be measured using a sphygmomanometer[0, 6, 18 months] Body composition (fat and fat free mass) using DXA scans.[0, 6, 18 months] Depression scale measured by the DASS‐21 questionnaire[0, 6, 18 months] Dietary intake and quality assessed using 7 day food diary and 24 hr recall analysis[0, 6, 18 months] Fasting blood glucose ; Clinical chemistry analyser ; ; ; ; [0, 6, 18 months] Fasting insulin levels as analysed using ELISA[0, 6, 18 months] Fasting lipids ; Clinical chemistry analyser, [0, 6, 18 months] Functional mobility ; Timed up and go test[0, 6, 18 months] Gut microbiome from faecal samples INCLUSION CRITERIA: Current night or rotating shift worker Currently working four night shifts every fortnight Aged greater than or equal to 25 years and less than or equal to 65 years at the start of the trial Weight stable in the past 3 months with weight change of no more than 5kg ; Opt in only for Melbourne participants[0, 6 months] HOMA‐IR from fasting blood samples[ 18 months post enrolment] Measures of pain a Subscale of AQoL[0, 6, 18 months] Physical activity patterns by wearing GENEActiv activity monitors and questionnaire (IPAQ)[0, 6, 18 months] Quality of Life using AQoL total score[0, 6, 18 months] Sleep outcomes will be measured using GENEActiv activity monitors and sleep diaries[0, 6, 18 months] Standard Shiftwork index questionnaire[0, 6, 18 months] Stress scale measured by the DASS‐21 questionnaire[0, 6 and 18 months post enrolment] Time to drop out (days) will be assessed by date of last contact i.e last recorded weight, last visit, official withdrawal[Anytime after baseline (days)] Waist circumference using an anthropometric retractable measuring tape [0, 6, 18 months] For Caucasian, BMI greater than or equal to 28 kg/m2 and less than or equal to 38 kg/m2, For Asians, BMI greater than or equal to 26 kg/m2 and less than or equal to 36 kg/m2. BMI is your body mass index and is worked out by using your weight [kg] and height [m2])