Impacts of Intermittent Fasting on Energy Balance and Associated Health Outcomes

• Status: Completed
• Trial end date: 2018-09-28
• Target enrollment: 0
• Participant gender: All

Summary

Obesity is a global concern with links to conditions such as diabetes. Historically, these conditions have been managed by reducing energy intake on a daily basis, which is often hampered by low adherence rates and compensatory reductions in physical activity. Intermittent fasting (IMF) has become popular as an alternative method of weight loss, where periods of normal eating are punctuated by days of fasting. However, despite its popularity, IMF is scarcely examined within the literature.

This study will examine the impact of IMF on energy balance and the associated health outcomes relating to conditions such as diabetes. To achieve this, 36 lean adults and 36 overweight/obese adults will be recruited, excluding those with conditions which may be adversely affected by fasting. Once enrolled, participants will complete a one month control phase, incorporating 12 days of diet and activity monitoring, to ensure their weight is stable before moving in to the intervention phase.

The intervention phase will begin with a lab protocol designed to examine body composition, resting metabolic rate and metabolic responses to two successive meals. Once completed, participants will be randomised to one of three diets which are listed below. Comparing the changes seen with diets 1 and 2 will provide the first direct comparison of IMF against more conventional strategies, while diet 3 will allow us to ascertain the role of weight loss in mediating any effects of IMF.

1. Daily calorie restriction - Reduce energy intake by 25% on a daily basis

2. IMF with weight loss - Alternate between 24 hour cycles of fasting and feeding with 150% of normal intake when feeding

3. IMF without weight loss - Alternate between 24 hour cycles of fasting and feeding with 200% of normal intake when feeding

All three diets will last for 20 consecutive days, with transitions between each 24 hour diet cycle occurring at 15:00 each day to allow at least one main meal per day. When fasting, participants will only be permitted water and black tea/coffee to eliminate energy intake. Once again physical activity and diet will be monitored for 12 days during the intervention to examine changes in energy expenditure and ensure compliance.

Having completed all 20 diet cycles participants will return to the laboratory to repeat the protocol described earlier. Comparing these results against the values seen before the intervention will then allow the effects of IMF to be identified and compared.

• Phase: N/A
• Accepts Healthy Volunteers?: Accepts Healthy Volunteers

Details

• Lead Sponsor: University of Bath
• Treatments: Lidocaine

Criteria

Inclusion Criteria:

• Body Mass Index of 20.5 kg/m2 or greater

• Stable body weight for preceding three months (<3 kg increase or decrease)

• Able and willing to safely comply with study procedures

• Be able to attend the laboratory and willing to participate in necessary protocols

• Be willing to undertake the durations of fasting required by the study

• Have the capacity and willingness to provide informed consent (oral and written)

Exclusion Criteria:

• Have a body weight greater than 120 kg

• Will be undertaking any other fasting practices during their participation in the study (can enrol once stable weight returns after fasting is completed)

• Currently engaged in or planning to engage in another weight management programme (e.g. weight watchers) or exercise programme (e.g. hypertrophy training or marathon training) during the study

• Have previously suffered or are suffering from an eating disorder as assessed using the Eating Disorder Examination Questionnaire, Version 6.0 (Fairburn & Beglin, 2008)

• Have been diagnosed with either type 1 or type 2 diabetes

• Undertaking any form of medical treatment which may interfere with study variables (e.g. chemotherapy, liposuction, taking metformin, statins/other lipid-lowering medications)

• Are peri-menopausal or menopausal (absence of menses for 3-24 months)

• Pregnant, recently pregnant (within last 6 months), planning to become pregnant (within next six months), or currently breastfeeding.

• Have donated more than 500 ml of blood in the last three months before the initial laboratory visit

• Lack of metal capacity or language skills to independently understand/follow the study protocol

• Physical disability which impacts study variables or ability to independently follow study protocol (e.g. paralysis)

• Cannot consume test meals due to intolerances (i.e. lactose)

• Report medical contraindications on the 'Physical Activity Readiness Questionnaire' and are unable to obtain medical approval for the treadmill test.