Interest in continuous glucose monitors (CGMs) is growing for use in evaluating real time glucose levels and in detecting extreme high and low values. A CGM is a small device primarily placed on the patient's upper arm or abdomen to measure glucose at frequent time intervals. While the accuracy of these devices is researched extensively, there are no large-scale studies evaluating the differences in the right and left arm in terms of device placement. In addition, intermittent fasting has gained popularity due to potential health benefits including reductions in weight, cholesterol, and blood glucose. However, there remains a shortage of studies researching the effect of short-term intermittent fasting on body fat.

The purpose of this study is to see if there is a difference between glucose levels in the right arm and left arm and to examine if short-term intermittent fasting may impact an individual's body fat percentage.

Continuous glucose monitoring (CGM) is an emerging field for diabetes management. CGM allows providers to individualize therapy by looking at real time glucose levels, detect changes in blood glucose and raise awareness for hypo- and hyperglycemic events.[1] Some CGM devices can be placed on the patient's arm to monitor blood glucose every few minutes. The data is then sent to a monitor for visualization. There are multiple Food and Drug Administration (FDA)- approved devices for continuous glucose monitoring. The FDA considers a device to be accurate if 99% of blood glucose measurements are within 20% of lab results and if 95% of blood glucose measurements are within 15% of lab results.[2]

The accuracy and precision of CGM devices is improving with several products gaining FDA approval. CGM data has been deemed accurate for self-use to adjusted insulin dosage, detection of hypoglycemia and determining the clinical response to therapy. However, events of low glucose readings and false alarms have been reported.[3]

An analysis conducted of the reports to the FDA Manufacturer and User Facility Device Experience (MAUDE) database since 2015 revealed over 25,000 complaints of CGM device inaccuracy.[4] Although CGM devices are researched extensively, there are no studies confirming that the measurements amongst the right arm and left arm are the same.

Intermittent fasting is an eating pattern in which individuals alternate between a period (~16 or more hours) of eliminated or restricted food intake, and a period of normal food intake. It has gained popularity in the public due to proposed health benefits including reductions in weight, cholesterol, and blood glucose.[6] There is published evidence that suggests beneficial effects of intermittent fasting on body fat. In an 8-week study, a significant decrease in fat mass was observed in the intermittent fasting group compared to the free-living group (-16.4 vs -2.8%).[8] However, this is the only human study assessing time-restrictive intermittent fasting and its effects on body fat, and there remains a shortage of high-quality evidence. We would like to further expand existing research by assessing the effect of short-term intermittent fasting on body fat.

This study is a controlled, prospective trial that aims to evaluate the difference in glucose readings between the right arm and left arm using continuous glucose monitors. In addition this study aims to evaluate the difference in percent body fat between short-term intermittent fasting and a free-living diet. Subjects will follow their designated diet for 12-14 days. The study will assess any changes in glucose levels, body fat percent, body mass index (BMI), weight, body composition before and after this 12-14 day study.

Inclusion Criteria:

• Adults 18-65 years of age
• Willing to wear CGM device for 12-14 days on both arms
• Have active health insurance
• Willing to refrain from any heat therapy for the duration of the study
• Having an interest to comply with the fasting requirements of the study as appropriate
• Willingness to maintain once daily email responses

Exclusion Criteria:

• Any active dermatologic condition on the upper arms
• Implanted medical devices (i.e. pacemaker)
• Critically ill or dialysis patients
• Planned magnetic resonance imaging screening, computed tomography scan, x-ray imaging or high-frequency electrical heat treatment during study period
• Current systemic infections
• Subjects who are unable to fully understand the study or consent process will not be included in the study due to the lack of a qualified medical translator
• Refusal to sign the informed consent document
• Pregnant, planned-pregnancy in the next 30 days, or breast-feeding
• Active eating disorder
• Taking any medications that have an increased risk of hypoglycemia (e.g. sulfonylureas, insulin, thiazolidinediones) as determined by the primary investigators
• Taking medications for obesity
• You have one of the following medical conditions that can cause rapid weight loss: rheumatoid arthritis, hyperthyroidism, irritable bowel syndrome, cancer, HIV, active tuberculosis, Addison's disease
• In an active weight loss program
• On a specialized diet (e.g. Weight Watchers, ketogenic diet, Atkins diet)
• Completed a specialized diet in the past 2 weeks (e.g. Weight Watchers, ketogenic diet, Atkins diet)
• History of adverse events (i.e. shaking, dizziness, fatigue, fainting) during any prior fasting experience
• Below the age of 18 years and above the age of 65 years