The Effect of Irregular Meal Pattern Providing Hypo-energetic Diet on Energy Expenditure and Metabolism

In this study we will compare the effect of two different meal patterns. Firstly, participants will consume a diet providing their estimated energy requirement for a 7 day standardisation period (6 meals per day). After a one day laboratory visit, this will be followed by a 14 day intervention period when participants will randomly follow a regular meal pattern (6 meals/d) or an irregular meal pattern (3-9 meals/d). Following a further laboratory visit day, they will then consume the previous standardisation diet for a further 3 days. The energy intake provided will be calculated to provide less energy than subjects are using which may result in approximately 2kg of weight loss. Participants will attend a screening visit in which they will complete questionnaires on medical health, eating habits and physical activity. In the laboratory visit, participants will be fasting and for 3 h after intake of a test drink, measurements will be taken of energy expenditure, fasting glucose, fasting gut hormones, fasting lipids and fasting insulin. A test meal will be offered. A questionnaire of subjective appetite ratings will be assessed while fasting, after the test drink, after the test meal, and during the intervention. Continuous interstitial glucose monitoring will be undertaken during the whole study period, Core body temperature will be measured before and after the intervention period. Also, wrist temperature will be measured during the whole study period.

Experimental protocol:

28 women who are a healthy weight or overweight (aged 18-45 years) will be recruited to a randomized parallel trial to follow one of two 14-d hypo-energetic diets. Firstly, participants will consume a diet providing their estimated energy requirement (6 meals/day) for a 7 day standardisation period. After a one day laboratory visit, this will be followed by a 14 day intervention period when participants will follow a regular meal pattern (6 meals/d) or an irregular meal pattern (3-9 meals/d) (energy deficit of 800kcal/ 24h in both diets) (identical foods provided on both interventions whilst otherwise free living). Following a further laboratory visit day, they will then consume the previous standardisation diet providing their estimated energy requirement (6 meals/day) for a further 3 days. All foods to be consumed during the study will be provided to free of charge. These will comprise foods commonly consumed in the British diet and will be consumed in amounts designed to provide 800kcal/24h less than estimated energy requirements in the intervention period. Participants will attend the laboratory visits fasting and a blood sample will be obtained for fasting glucose, insulin and lipids. A test drink will then be given and over the following three hours measurements will be taken of energy expenditure (TEF). An ad libitum pasta test meal will be offered three hours after the test drink has been given. Subjective appetite ratings will be assessed while fasting, after the test drink, after the ad libitum meal, and during the intervention. Continuous interstitial glucose monitoring will be undertaken throughout the study. Ambulatory activity pattern measurement will be assessed in the intervention period. Core body temperature will be measured during the last 3 days of the first standardisation period, and during the final three standardisation days. Peripheral body temperature will be measured throughout the study period using a small i- button secured to the wrist. The study will commence at the early phase of the menstrual cycle (days1-7). A constant sleep-wake (and light exposure) routine will be followed for the whole study period which will be assessed by a written questionnaire form

Eligibility Criteria:
Inclusion Criteria:

* BMI between 18.5 and 30 kg/m2,
* Age between 18 and 45y,
* Non-smokers,
* Non high-alcohol consumers (≥ 14 units/week),
* Regular menstruation or on the oral contraceptive pills,
* Their weight is stable during the previous 3 months,
* No self-reported history of serious medical conditions and not under medication.

Exclusion Criteria:

* Pregnant or lactating women
* Smokers
* High-alcohol consumers (≥ 14 units/week)
* Subjects with high score for depression using Becks Depression Inventory
* subjects Eating Attitudes Test (EAT-26) score \>20
* Subjects who on diet or seeking to lose weight
* Subjects with high consumption of coffee or tea \> 3 cups/day