Intermittent fasting has been getting a lot of attention lately on social media and the news. Some of the suggested benefits include weight loss, improved metabolism, increased energy levels, and fat loss. Are these benefits accurate? What is the research behind intermittent fasting? Let’s explore this trend together!
Fasting is nothing new to humanity! People have been fasting for centuries. Some fast due to religious or cultural reasons, others may fast because of a famine. Some also fast to lose weight and/or improve their health.
Fasting can be done in a variety of ways, and the definitions of fasting seem to change depending on who you ask.
Intermittent fasting is an eating pattern that focuses on when you eat, rather than on what you eat. Essentially, it is a cycle of periods of eating and periods of fasting over a certain period of time. Some intermittent fasters may fast for 12-16 hours per day and eat only within a 8-12 hour window. Other intermittent fasters may fast for 24 hours, 1-3 days per week, and eat normally on the other days of the week. Fasting can mean not eating or drinking any calories, or it can mean consuming very few calories (i.e. 500-600 calories per day).
On the other hand of the dieting spectrum, we have caloric restriction. This involves a restriction of total calories per day.
Interestingly, there is no evidence to suggest that intermittent fasting is any more or less effective than other calorie-restricted diets on weight loss or metabolic health markers such as blood glucose, cholesterol, and insulin levels. There is also insufficient data on the effects of intermittent fasting on sleep and physical activity, which are other important health markers. Interestingly, there is some evidence that skipping breakfast is associated with a higher body mass index (BMI), higher LDL-cholesterol, and increased insulin resistance. But this evidence is limited and the mechanism between skipping breakfasts and these results remains unclear.
At the end of the day, there are very few diets that have overwhelming, conclusive evidence for their efficacy on weight management and/or improving health - and intermittent fasting is no exception. Current evidence is very limited and conflicting, so more in-depth and long term research is definitely warranted.
As with all diets, questions arise…
Is it sustainable long term?
As with any restrictive diet, intermittent fasting takes a lot of work and planning, and may not be suitable for your lifestyle. Think of whether or not this pattern would be practical for you, with the possibility of intense hunger on fasting days. Restrictive diets often provide short term results (e.g. in terms of weight loss) but aren’t sustainable long term, which can often result in regain of the weight initially lost (and sometimes even gaining more weight than where you started!). Realistic, sustainable, long-term changes often involve making small modifications to your diet and lifestyle over time.
Is it healthy?
Health is so much more than weight! Mental health, physical health, emotional health, and social health are all equally important. From a nutritional perspective, the fact that intermittent fasting doesn’t examine what you eat (just when you eat it), makes us weary. At the end of the day, your body still needs adequate macronutrients (carbohydrates, fat, and protein) and micronutrients (vitamins and minerals) to function optimally, and what you eat (such as more vegetables, fruit, whole grains, and vegetarian protein sources) can either increase or decrease your risk for chronic diseases. As well, intermittent fasting may not be for everyone (e.g. children, pregnant/breastfeeding women, diabetics, seniors, underweight individuals, etc.), which is why it is always important to check with your physician and/or dietitian before starting a new diet.
Remember, health isn’t just about physical health. Following a restrictive eating pattern, like intermittent fasting, may impact your emotional and mental well being. You may also find yourself missing out on meals with family and/or friends or feeling socially isolated as you are following a diet that no one else in your household does. Not only this, but restrictive dieting may affect your relationship with food and you could fall into a disordered eating pattern. ***If you have feelings of guilt and/or shame about eating, are obsessing about food, or believe that what you eat reflects your value as a human being - we strongly suggest you seek help and guidance from a dietitian and/or physician to build a healthier relationship with food!
The final word...
At the end of the day, you have to decide what works best for you. If intermittent fasting is an effective, sustainable diet which you can follow safely and fits well into your lifestyle, then go right ahead! But if intermittent fasting is unsustainable, affecting your health, or is socially isolating - it’s likely not a good fit for you. We prefer to recommend a non-diet dietary approach - a focus on eating healthy and being active, in a way that you enjoy and suits your lifestyle, and promotes a healthy relationship with food. If you are looking for help with making healthy, long-term lifestyle changes, book an appointment with Alex or Stephanie today!
“Intermittent Fasting and Human Metabolic Health” (Journal of the Academy of Nutrition and Dietetics)
“Impact of intermittent fasting on health and disease processes” (Ageing Research Reviews)
“Intermittent fasting and its influence on health” (Physical Activity Review)
“Weight-Loss Outcomes: A Systematic Review and Meta-Analysis of Intermittent Energy Restriction trials Lasting a Minimum of 6 Months” (Nutrients)
“Intermittent Fasting Diets” (Dietetically Speaking)
“Is Fasting Healthy?” (PEN)
“Intermittent Fasting and Human Metabolic Health” (Patterson et al., Journal of the Academy of Nutrition and Dietetics)