Evaluation of the Effect of Time-Restricted Feeding and Mediterranean Diet Model in Women With Polycystic Ovary Syndrome

Currently, there is still insufficient data to support the long-term efficacy, safety, and health benefits of time-restricted feeding models in women diagnosed with Polycystic ovary syndrome (PCOS), and further studies are needed to test and validate the effects of long-term dietary management in PCOS. On the other hand, similarly, studies investigating the effects of the Mediterranean Diet on body composition and dietary intake in women with PCOS are limited. The primary aim of this research is to examine the effect of time-restricted feeding and the Mediterranean diet model on body composition and dietary intake in adult women diagnosed with PCOS. The secondary aim is to evaluate the effect of different dietary models on quality of life in women diagnosed with PCOS.

PCOS is the most common female endocrine disorder and is characterized by chronic anovulation, hyperandrogenism, and polycystic ovaries. The term PCOS was first used in 1935 when menstrual irregularities, decreased fertility, obesity, and hirsutism were reported in patients. Amenorrhea and resulting infertility, obesity, and male-pattern hair growth were listed among the symptoms. Diagnosis was made in the 1970s and 1980s by measuring luteinizing hormone (LH) levels. At a conference organized by the National Institute of Health in 1990, it was stated that the primary diagnostic criteria for PCOS are infrequent ovulation and symptoms of androgen excess. Since 2003, PCOS has been diagnosed when at least two of the three Rotterdam criteria are present. Clinical hyperandrogenism (with hirsutism, acne, seborrhea, and alopecia) and/or high circulating androgen levels, the presence of ovarian cysts assessed by ultrasound examination, and anovulation and/or oligo-amenorrhea are criteria that lead to diagnosis. Various interventions (pharmacological, non-pharmacological, or surgical) exist to reduce PCOS symptoms. Metformin is a commonly used insulin sensitizer in PCOS patients with insulin resistance, but gastrointestinal side effects limit its use as a first-line treatment for long-term management. The international evidence-based guidelines for the assessment and management of PCOS, updated in 2018, recommend diet and exercise therapies as the first step in management. These guidelines focus on improving diagnostic accuracy by significantly improving individual diagnostic criteria; The focus is on reducing unnecessary testing; increasing emphasis on education, lifestyle changes, emotional well-being and quality of life; and highlighting evidence-based medical treatment and cheaper and safer fertility management. Diet and exercise interventions are important because 60% of women with PCOS are overweight or obese. Recently, various dietary interventions are being tried for the management of PCOS. Fasting is known as one of the oldest traditions in the world and is practiced among various communities for cultural or religious reasons. Fasting has also been used as a method of treating diseases in the past. Hippocrates, considered the father of modern medicine, emphasized the importance of fasting during illness with his words, "To eat when you are sick is to feed your sickness". Intermittent fasting (IF), that is, periods of voluntary abstinence from food and drink, is known as an ancient practice followed in different forms by many populations worldwide. With intermittent fasting, there is a state of fasting or restricted eating at certain times of the day or on certain days of the week. IF; It can be implemented in three different types: alternate-day fasting, 5:2 diet, and time-restricted eating (TRF). Alternate-day fasting involves alternating days when food and drinks are consumed with fasting days when energy-containing foods or drinks are not consumed. In alternate-day fasting, approximately 20-25% of the energy requirement is met on fasting days. Modified fasting diet is also known as the 5:2 method. In this nutritional model, 2 non-consecutive days of the week involve a very low-calorie diet, while the other 5 days include normal energy requirements without energy restriction. Another approach is time-restricted eating, which is used to describe an eating pattern where food intake is limited to a time window of 8 hours or less each day. Among intermittent fasting diets, the TRF diet is a lifestyle intervention that limits the duration of food intake to a fixed number of hours. Welton et al. reported that the ideal fasting duration for positive weight change is 16 hours. In recent years, small-scale human studies demonstrating the importance of time-restricted eating have become widespread. Most of these studies have revealed the beneficial aspects of intermittent fasting in human metabolism, as in animal studies. With TRF, reductions in energy intake, body weight, body fat, blood sugar, triglycerides, glucose tolerance, and inflammatory markers have been observed. It has been found that IF may be beneficial in reducing body weight, improving insulin resistance, and reducing infection by regulating the circadian rhythm, gut microbial composition, and metabolism. Disruption in the circadian rhythm; Because it is associated with insulin resistance, excessive androgen production, increased Anti-Müllerian Hormone (AMH) levels, and apoptosis of granulosa cells, TRF is predicted to alleviate PCOS by improving the circadian rhythm. In addition, IF diets can improve PCOS by reducing insulin resistance through the stimulation of AMP-activated protein kinase (AMPK). In a recent review, it was found that in overweight/obese women with PCOS, the 5:2 diet and TRF promised improvements in menstrual regulation by significantly reducing the free androgen index and increasing sex hormone binding globulin. In a study in which 30 women diagnosed with PCOS underwent a 6-week, 8-hour TRF diet intervention, baseline (pre-diet) and post-diet findings were compared. It was found that after the diet, body mass index (BMI) and body weight decreased significantly, HOMA-IR improved significantly, and metabolic parameters related to glucose and lipid profiles also showed significant improvements after the diet. The Mediterranean diet is considered a health-promoting dietary model due to its unique characteristics, including regular consumption of unsaturated fats, low glycemic index carbohydrates, high amounts of fiber, vitamins, antioxidants, and moderate amounts of animal-derived proteins. In addition to weight loss, it has been reported to have anti-inflammatory activity due to the production of short-chain fatty acids stimulated by dietary fiber. The Mediterranean diet pyramid recommends foods to be consumed daily, weekly, and monthly. It is recommended that fish and seafood be consumed at least twice a week, white meat in 2 servings, eggs in 2-4 servings, red meat in less than 2 servings, processed meat in 1 serving or less, and desserts in less than 3 servings. Daily, it is recommended that dairy products be consumed in 2 servings, and olive oil-based seeds and nuts in 1-2 servings.