Intermittent Fasting

What is Intermittent Fasting?

Fasting has been used for centuries for religious practice and as a peaceful protest strategy. Recently, intermittent fasting has become one of the most popular and talked about health and fitness trends worldwide. Intermittent Fasting consists of cycles between periods of fasting and eating. The most common cycles involve a 16 hour daily fast or a 24 hour fast twice per week. The 16 hour fast involves skipping breakfast and snacks while consuming a later and larger lunch and dinner within an 8 hour period.

How Did Intermittent Fasting Become Popular?

Intermittent fasting is credited as an ‘easy’ calorie restriction. However, in animal studies, intermittent fasting was not more effective than regular calorie restriction in reducing blood glucose, triglycerides, or cholesterol. It involves less meal planning, preparation and clean up because you are consuming fewer meals. Intermittent fasting may be easier than calorie restriction for some people as it creates clear cut rules around food.

Are There Any Adverse Effects of Intermittent Fasting?

Going long periods of time without eating can lead to overeating or feeling out of control around food when you do eat. The diet can be frustrating as overeating is common and it is extremely difficult to maintain. Fasting can cause dizziness, fatigue, nausea, feeling lightheaded and even fainting. Some participants in research on intermittent fasting reported feeling cold, irritable, low energy, hungry, and weak. Skipping breakfast may cause a decrease in concentration and school or work performance. Long term fasting can lead to an abnormal menstrual cycle. Research is lacking on the long-term benefits or adverse effects of intermittent fasting. It is unclear whether this diet is safe for long-term use.

Maintenance of Intermittent Fasting?

Similar to most fad diets, intermittent fasting is hard to stick with. This may result in fast weight loss with fast weight regain following the diet. This is common among fad diets and is referred to as ‘yo-yo’ dieting. ‘Yo-yo’ dieting can result in sarcopenic obesity (loss of muscle mass and increases in fat mass), poor cardiovascular health, high blood pressure, heart rate, blood glucose, lipids, and insulin. It is possible that intermittent fasting may make it harder to manage depression and anxiety.

Physical Activity & Intermittent Fasting

Intermittent Fasting is extremely popular with some athletes, most notably bodybuilders and personal trainers with a high social media presence. Research on athletes participating in Ramadan has shown increased fatigue and decreased performance. There is conflicting research on whether intermittent fasting allows you to retain muscle mass while losing weight compared to traditional diets.

In summary

I would not suggest intermittent fasting as it can be a very frustrating cycle. People who intermittently fast may feel as though they have failed when really, it’s the diet that has failed. This diet does not honour all of the reasons we eat and can result in a lot of negatives such as dizziness, lack of concentration, and fatigue. Fad diets, such as intermittent fasting can lead us to believe that our weight is a good indication of health status. Instead, it is important to find a routine that helps you feel your best physically and mentally and trust that this will allow your weight to settle at a place that is right for you.

Questions about your diet and nutrition needs? All University of Guelph students have access to Student Wellness Services nutrition services (free and fee-based options are available). Students can access these services in three ways: