Intermittent Fasting Compared to Continuous Energy Restriction on Body Weight Loss

Effectiveness of Intermittent Fasting Compared to Continuous Energy Restriction on Body Weight Loss Among Overweight/Obese Adults: a Randomized Controlled Trial

Obesity remains a major public health challenge. Intermittent fasting continues to gain popularity compared to continuous energy restriction as a weight-loss approach for cardiometabolic health. Studies to date comparing intermittent energy restriction (IER) and continuous energy restriction (CER) have not been investigated on weight loss and cardiometabolic risk markers in low-income countries like Nepal. The main objective of this study is to compare the effectiveness of IER versus CER diet on weight loss and cardiometabolic risk markers over the course of six months among overweight/obese Nepalese population. This study will adopt a parallel arm, open-label, randomized control trial design. The study duration will be six months from baseline to endline. A total of 112 overweight and obese participants, aged 18-64 years, with waist circumference >90 cm (men) and >80 cm (women) will be enrolled in the study. Interested participants will be approached through social media and consecutively enrolled and assigned to either IER group (n=56) or CER group (n=56) randomly. Participants will be provided Mediterranean pattern dietary intervention including two groups: IER group will receive 5:2 diet pattern (5 day without energy restriction and 2 days with 75% energy restriction, net weekly energy deficit ~25%), and CER group with a low-calorie diet (daily energy deficit ~25%) over the course of six months. Both IER and CER group will be provided personalized diet plan, portion size, nutrition counseling focus on dietary guidance, motivational strategies, and personal goal setting for behavior change with educational materials. Baseline data will be collected using a structured questionnaire and the biochemical tests will be done. Baseline data will be collected at the time of enrollment, midline in three months, and end-line data collection in six months. The primary outcome of this study will be the change in weight loss between IER and CER groups. The secondary outcome measure will be to evaluate changes in nutritional composition, eating behavior, and cardiometabolic risk markers between IER and CER group over six months. Data will be entered using Epidata Software and transferred to the Stata/MP version 14.1 for further analysis. Data will be analyzed using an intention-to-treat basis. Independent t-test and, repeated measures ANOVA will be used to estimate changes between-group comparisons. The significance level will be assumed at p<0.05

Overweight and obesity remain a major chronic health problem globally. The development of overweight and obesity is associated with various comorbidities including cardiovascular disease (CVD), dyslipidemia, hypertension, insulin resistance, certain cancers, and sleep apnea. Obesity is a strong modifiable risk factor for CVD, the leading cause of death worldwide. Dietary management is a cornerstone in the prevention, treatment, and control of overweight and obesity, CVD, and metabolic risk factors. Healthy dietary habits reduce the risk of several chronic lifestyle-related diseases as well as meet the demand for essential nutrients to the body to keep healthy. Many dietary guidelines for the management of overweight and obesity in the general population recommended the reduction of body weight through calorie restriction, increase energy expenditure or followed both approaches. The most common method of weight loss has been daily, or continuous energy restriction (CER), which involves individuals restricting their energy restriction on daily basis by anywhere between 15-60%. Although CER is the most widely recommended calorie restriction approach for body weight loss and prevention of overweight and obesity, recent years have seen a surge in popularity of eating patterns including intermittent energy restriction (IER) as an alternative to CER due to its less restrictive nature and potential for higher rates of adherence. IER is an alternative weight loss method that may prove useful for individuals who find continued energy restriction difficult to maintain. Recent studies have shown IER to be comparable to CER in achieving weight loss in overweight and obese populations with the mean weight loss being 3-5 kg over 20 weeks. IER is considered to be effective for the management of obesity because IER requires the individual to focus on the energy-restricted for defined days during the week which is potentially more feasible than the standard approach of CER which is associated with poor compliance, and IER diet pattern have many beneficial metabolic effects achieved with weight loss and energy restriction when the person is no undergo negative energy balance. Many peoples are worried about their increased body weight due to obesity-related adverse outcomes including coronary heart disease, type 2 diabetes, and metabolic disorder. There is a knowledge gap of evidence-based dietary patterns used for weight loss diet plan in the Nepalese context. The effectiveness IER using a 2-day severe energy-restricted strategy with 5 days of habitual eating pattern compared to CER has not been yet investigated within the Nepalese population. Therefore, the investigators intended to investigate the effectiveness of an IER diet using 2-day severe energy-restricted with 5 days of habitual eating pattern compared to a CER diet over six months.

The proposed study is a parallel arm, randomized controlled trial compare two different dietary patterns: 1) intermittent energy-restriction (IER) diet also known as intermittent fasting (5:2 eating pattern: 5 days of habitual intake and 2 very low energy diet on two non-consecutive days (Mondays and Thursdays) per week, and 2) Continuous (daily) energy-restricted diet (CER) on the reduction of body weight, and cardiometabolic risk factors among overweight/obese Nepalese population (Figure 2). This study will adopt a parallel randomized trial design with an equal allocation of participants between the IER and CER arm. The participants will be recruited from the general population through social media advertisements. The study will be carried out for six months, from baseline data collection, follow-up midline data collection, and end-line data collection for outcome measure.

Intermittent energy restricted (IER) group: IER group will receive 5:2 diet pattern (5 day without energy restriction and 2 days with 75% energy restriction, net weekly energy deficit ~25%)

Continuous energy restricted (CER) group: CER group with a low-calorie diet (daily energy deficit ~25%) over the course of six months.

Participants in the IER group will be provided menus on fasting day that provide ~25% of the individual energy requirement (400 kcal/day for females and 600 kcal/day for males) that means ~75% energy restriction per week (Sundfør et al., 2018; Svendsen, 2018; Templeman, Gonzalez, Thompson, & Betts, 2020). The recommended fasting day may be on two non-consecutive days (Mondays and Thursdays) per week and remaining five days of the week will be based on the usual diet plan. All participants will be instructed to complete all food by 12 pm and then fast until 8 am the following day (Svendsen, 2018).Thus, the weekly average calorie intake will correspond to ~75% of the normal energy requirements. They will receive a diet plan that recommended ~50 gm protein/day from chicken breast, lean meat, lean fish, fat-free yogurt, cottage cheese, egg or legumes, and vegetables to increase satiety on fasting days.

Participants in the CER group will be advised to reduce total energy intake to 1200-1550 kcal in all seven days a week. They will be provided diet plan calculated in relation to each person's estimated energy requirements. Menus will be divided into breakfast, lunch, dinner, and snacks in line with their individualized energy recommendations. They will be requested to consume ~75% of the individual energy requirements daily (25% energy restriction of calculated baseline energy requirements daily) over six months. Thus, the overall energy restriction will similar between the groups at an estimated reduction of 25% of requirements. Participants will be randomized in a 1:1 ratio, and assigned to an intermittent or continuous energy restriction group randomly.

The primary outcome of this study will be the change in reduction of body weight between IER diet using 2-day severe energy-restricted with 5 days of habitual eating pattern compared to a CER diet over three months.

Inclusion Criteria: Men and women aged 18 years or above with body mass index (BMI) >25 kg/m2 Those who give consent to participate in our intervention study Exclusion Criteria: Those who are pregnant women, lactating women, or planning to become pregnant during the course of study. Those who are severely ill or more than two comorbidities such as major psychiatric disorders, previous gastric surgery, haematological disorders, insomnia, acute excerabation of chronic obstructive pulmonary disease, asthma, respiratorty tract infections, and diabetes patients if treated with insulin or hypoglycemic agents. Those who have any plan to migrate from the study area for at least three months Use of anti-obesity drugs or other drugs affecting body weight Eating disorder, alcohol or drug abuse that could contribute to difficulties with study procedures

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