Overweight 10% weight reduction over 6 months and

Overweight and obesity is a growing health problem globally. A 2011 survey1 found that in the Republic of Ireland 24% of adults aged 18 – 64 were obese and a further 37% were overweight. Overweight and obesity has serious implications for the health of the individual2. Increased morbidity, hypertension, increased risk of diabetes mellitus and coronary heart disease are just some of the risks associated with overweight and obesity. Aside from the cost to the individual there is also a significant cost to society. A 2009 study3 estimated that the cost of overweight and obesity due to healthcare costs and lost productivity amounted to 1.16 Billion Euro in that year in the Republic of Ireland. Research into interventions for weight loss and weight maintenance is a high priority area in public health.In simple terms; weight gain occurs when daily energy intake (DEI) exceeds total daily energy expenditure (TDEE). Common weight loss strategies involve increasing the TDEE through exercise or reducing the DEI by modifying the diet, usually a combination of the two. Various interventions have been evaluated and evidence based clinical guidelines for weight loss have been issued by multiple state and international bodies2, 4-6. A reduction by 5% of initial weight is considered result in clinically significant reduction in risk factors7. Guidelines generally recommend a target of 10% weight reduction over 6 months and maintained at 12 months.Currently used interventions are reasonably effective in causing weight loss; however, many people regain much of the lost weight. A review of weight loss clinical trials8 indicated that reduced energy diets resulted in mean weight loss of between 5 – 9%, and that 3 – 6 % of weight loss was maintained. There is a need for improved weight maintenance strategies and research into alternative approaches to weight management has been developing in recent years. One such approach is intermittent fasting.Intermittent fasting (IF) or intermittent energy restriction (IER) is a regimen for reducing calorie intake by fasting or following a very low calorie diet (VLCD) on certain days interspersed between days of ad libitum caloric intake, or intake meeting daily energy requirements. This differs from normal regimen where the daily calorie intake is reduced by a constant but lesser amount; termed continuous energy restriction (CER)IF as a method of weight loss, or as a way of achieving health benefits in normal weight individuals has become a popular idea in recent years. Google trends show the popularity of the term “intermittent fasting” has been increasing steadily. Despite mainstream popularity, intermittent energy restriction is an under-researched area. Reviews of the available evidence have indicated that IER results in comparable weight loss to CER over short time periods (3 – 6 months)9-12. However, no trials have been conducted to assess the viability of IER as a weight maintenance approach.Research Question:• Does an intermittent energy restriction diet reduce weight regain following weight loss?Aims:• To compare the weight regained by a group following an IER weight maintenance intervention to a group with no intervention.Hypothesis: A light intermittent energy restricted diet will be easy for individuals to follow whilst also being effective in maintaining weight lost.2. Study design:A randomized comparative trial will be used to assess the effect on weight regain of an IER based weight maintenance intervention. Participants will follow a 6 month CER weight-loss diet as per the recommendations of current clinical guidelines16. Males will follow a 1600 kcal daily diet and females a 1200 kcal daily diet. Diets will not be directly provided but participants will be provided with dietary advice and sample meal plans. Additionally, participants will be given exercise advice and set their own exercise plans. They will be advised to gradually increase levels of exercise with an eventual target of at least 30 minutes of moderate exercise 5 days per week. Participants will monitor their own adherence to diet and exercise targets with a weekly diary. Weight loss will be measured at 6 months.Following the initial weight loss period those participants having achieved a minimum of 5% reduction from initial weight will be randomized into two groups. Both group will be given dietary advice and will be advised to maintain exercise targets. One group will also be instructed to follow a 6:1 IER diet. This will involve 6 days of ad libitum intake and one “fast day” on which they consume one evening meal only. This group will maintain a weekly diary monitoring adherence. Diet will not be directly provided, participants will use the sample meal plans to guide them for the evening meal on the fast day and will be advised not to compensate with a larger than normal meal. Weight will be measured and differences in weight regain assessed at 12 months.The study design is simple and manageable given the resources likely to be available to a student, however there are some limitations. Having all participants follow a diet with the same caloric intake is not optimal. Ideally the resting metabolic rate would be calculated using a predictive equation13 and then the TDEE would be estimated. The participants would then restrict their intake to a percentage of the TDEE. This approach however would require significant time from a dietician which may be infeasible.The participants’ weight and BMI will be measured at the outset of the trial, 6 months and at 12 months. Aside from this, the weekly weight change and adherence to diet and exercise plans will be self-reported. Self-reported data may be prone to exaggeration of adherence and weightloss, and will therefore be of reduced value. Recording adherence and weight loss data through fortnightly or monthly interviews would increase accuracy of the data but also the costs of the trial and demands on the participants.The data from the diaries from the weight loss phase will not be considered for the purposes of this trial. Only the diaries for weight maintenance phase from the IER group will be considered to assess adherence. The other diaries serve only as a motivational tool as per clinical guidelines.3. Study Population and SamplingThe population studied will be overweight and obese students studying at University College Cork. Participants will be recruited by sending a university wide email and posting notices around the campus. UCC had a student population of 21000 in 201614. Statistics indicate that around 12800 of these students will be overweight or obese.A multistage sampling scheme will be used; from the respondents to the advertisements participants will be selected by simple random sampling. Following the initial weight loss phase those with clinically insignificant weight loss will be excluded. Participants will be stratified by pre weight loss BMI into 3 categories corresponding to overweight, obese class I and obese class II and randomized into two groups for the second phase of the trial.A statistician will be consulted regarding the power calculations for determining sample size. One important factor to consider will be the high attrition rate in clinical weight loss trials15 and the need to increase sample size to compensate. A preliminary target of 100 – 150 participants is suggested. This number is comparable to other trials of IER diets conducted recently9-12.Exclusions:- Currently undergoing a clinical or independent weight loss intervention- Obese class III (>40 BMI) or normal weight and below (<25 BMI)- Currently on medication associated with weight loss or gain- Preexisting diabetes mellitus, Major CVD, musculoskeletal, respiratory or psychiatric illness- Those not having achieved clinically significant weight loss (>5%) in the weight loss phase4. Data collection and quality assuranceThe participants will meet with a research assistant pre-trial, at 6 and 12 months. At each meeting the participants’ height and weight will be measured and BMI calculated. Weight will be measured using a clinical standard floor scales e.g. SECA brand. Data will be entered directly into a clinical data management software suite such as OpenClinica17.Adherence to the IER weight maintenance diet will be assessed using the diaries and any gaps will be filled by discussing with the participant during the final measurement session. Data from participants with low adherence will be excluded.There is the possibility to expand the trial by including blood pressure or % body fat measurements, but the primary factor of interest is overall weight and BMI.5. Data analysisMean weight at 12 months will be subtracted from mean weight at 6 months to give mean re-gain for each group. An independent samples T test will be used to compare the mean re-gain for the two groups.6. Ethical considerationsPrior to recruitment informed consent will be sought from all potential participants. All participants will read, sign and return an information and consent form. Data collection and storage methods will ensure participant confidentiality and anonymity. Participant data will be recorded directly into password protected forms in a CDM suite. Only anonymized data will be used in publications.Participants may personally benefit from improved health due to weight loss. Health risks during the weight loss phase of the trial are believed to be minimal. Individuals deemed to have increased risks due to factors outlined section 3 will be excluded. Ethical approval will be sought

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