What’s your experience with intermittent fasting? Have you heard of it? Tried it? Think it’s all just a bunch of hype?

I first heard of intermittent fasting from my functional medicine doctor who recommended it as a possible aid in fat loss. My weight is in the normal range, but according to his diabolical body fat analysis tool, I do have some fat that needs to go (and I need to add more muscle too).

So that was my first introduction to intermittent fasting (IF) and what he recommended is probably the most common version: a shortened feeding window, otherwise known as Time-Restricted Feeding. There are all sorts of variations on this version of IF, but most involve 6-8 hours of eating and then 16-18 hours of fasting. Considering that you have time after dinner and before bed, then sleeping time, fasting for 16 hours isn’t as difficult as it might seem at first blush.

I enjoy exercising first thing in the morning (well, after coffee) and on an empty stomach so this version of fasting has worked very well for me for many years. Occasionally, I wake up and just want to eat something. Maybe I have some yummy biscuits or scones lying around and so I’ll have one with my coffee simply because it looks good – but I always regret it. Seems my body very much likes my coffee-only breakfast and I’m happy with it from a practical standpoint because it’s one less meal for me to prepare and clean up. Or maybe I’ve just become used to it? BUT – it has done nothing to change my body composition. I like this version of IF because it’s convenient to only prepare two meals a day and I feel good following this plan. However, I don’t know that it’s doing anything positive for my health.

In the years since first learning of intermittent fasting from my doctor, IF has really gone mainstream and there are lots of recommendations, opinions and philosophies surrounding this way of eating. This post will by no means be a comprehensive look at IF, nor is it a recommendation, but I do hope to provide you with a basic outline of intermittent fasting, how it might help you and give you a little scientific evidence to its effectiveness.

Let’s start with the different versions of IF:

1. Alternate Day Fasting – this is just like it sounds – you eat one day and fast the next. There are versions of this that include eating for two days, fasting for three, eating for two, fasting for three and so on. There is also a version that involves eating normally for two days, fasting for one day, then eating very restricted calories for the remainder of the week. That last one sounds way too complicated to me! Part of the beauty of IF is that it can simplify your life.
2. Time Restricted Feeding (which might be referred to as the 18:6 method or 19:5 or even 12:12) – the bottom line here is that you fast for the majority of the day and eat within a restricted window. Within Time Restricted Feeding, there are two variations:
   1. Skipping Breakfast – this is undeniably the most popular version of intermittent fasting and involves not eating until around lunch time. Some people enjoy coffee with a little cream or collagen, keeping the calorie count under 50. Others just drink water or herbal tea. Either way, you don’t enjoy your first real meal of the day until somewhere around 11-1.
   2. Skipping Dinner – this version was new to me, has some compelling evidence behind it and is, in my opinion, the most difficult version of fasting if you have a family. More on this below.
3. Fasting-Mimicking Diets – introduced by Dr. Valter Longo and used to treat serious diseases, including Alzheimers, Epilepsy, Parkinson’s and Cancer. You can buy kits that contain all your food, you can buy meal plans, or you can simply follow his outline with regard to calorie counts and specific macro- and micro-nutritients to consume each day. You are never fasting completely for an entire day, but the calories are restricted and it’s a very specific eating plan designed to make the body think it is fasting. I have heard great success stories around this plan and am considering trying it this summer when all of my family will be away at camp and I only have to worry about food for me. I think if I were cooking for my family and watching them eat, I would have a hard time with this because I just like eating.

I’ll spend the majority of the space here talking about Time Restricted Feeding because it is the most common and arguably the easiest form of IF to implement.

What the research says:

There is currently a lot of research being conducted on intermittent fasting – in mice and rats. There is some research being done in humans, but not nearly enough to draw any solid, statistically-significant conclusions. We learn a lot from mice, but it’s important to remember that mice are not the same as humans.

A variety of beneficial health effects have been seen in these animal models:

• Fasting can counteract disease processes and improve functional outcomes in a wide range of age-related disorders including diabetes, cardiovascular disease, cancers and neurological disorders such as Alzheimer’s disease, Parkinson’s disease and stroke.
• One of the beneficial process we see happening inside the body during intermittent fasting is called autophagy, which sounds scary, but it’s actually a good thing and something a healthy body does normally. Autophagy is a process by which the cell (the building blocks of the body) becomes more efficient, getting rid of old, poorly-functioning parts. This is an important process for boosting immunity, protecting against autoimmunity and reducing inflammation. During IF, autophagy can be enhanced and therein lies the benefit. The good news is that autophagy can be enhanced by regular exercise and good, healthy sleep without any fasting required.

Human studies have been much less frequent than mice studies and the results are not as encouraging. The most prevalent positive effect of IF in humans is weight loss, though this has been attributed almost entirely to the reduced calorie intake that generally happens with IF. There are other health benefits, but they can all be tied to the weight loss: improved insulin sensitivity and reduced cardiovascular risk factors. Don’t get me wrong – these are good things for sure, but IF is not the only way to achieve these same results. Keep in mind that these are the documented positive results from actual scientific studies. There are many more benefits that have been reported by functional medicine practitioners and anecdotally by people actually practicing IF.

Some potential positive effects of IF (not scientifically proven):

• Balanced hormones – primarily we’re talking about insulin sensitivity going up (which is good), and balancing of grehlin and leptin (the so-called fullness and hunger hormones).
• Increased secretion of growth hormone which promotes fat loss. Chronically high cortisol causes the opposite effect – an increase in inflammation, which causes lean muscle breakdown and fat storage
• Extended fasting, like alternate day fasting, has been shown to help with the elimination of type 2 diabetes, metabolic syndrome and obesity
• Reduces gut inflammation, primarily by helping to balance the microbiome

I want to note that these potential benefits are HUGE and should not be discounted simply because they have not been proven in large, peer-reviewed scientific studies. It is very difficult to conduct such a study because there are so many complicating factors. Correlation doesn’t equal causation. Meaning, just because people following an intermittent fasting protocol see a reduction in inflammation and increase in insulin sensitivity (for instance), doesn’t mean that the fasting caused those results. But it might have. It’s very hard to know. You would have to control for so many different factors and count on the study participants being 100% compliant, which is just about nearly impossible.

Let’s loop back around to the different types of intermittent fasting for a moment. Remember, I talked about Time-Restricted Feeding being the most popular form of fasting? Most of us who practice IF extend our bedtime fast through the morning hours and begin eating mid-day. It turns out that the opposite of what most of us do, Circadian Feeding or Early Time-Restricted Feeding (skipping dinner) may show more promise with regards to real health benefits. It’s just harder to implement for some.

Eating to match the natural rise and fall of your cortisol levels has been shown to be very beneficial to the microbiome, increases fat burning and helps to reset the circadian rhythms, which is particularly beneficial if you have trouble sleeping. For most people, our cortisol rises with the sun, around 7 AM and begins to drop around 3 PM. So to match your feeding window to this rhythm, you would begin eating upon waking, eat most of your calories early in the day, say by noon, and have a light dinner around 3 or 4 PM. The old adage, “Eat breakfast like a king, lunch like a prince and dinner like a pauper” follows this line of research.

The question is: Does that sound practical or sustainable to you? Perhaps if you are someone who does shift work or if you are single and only responsible for feeding yourself, or have a very flexible family, you could make this work. Remember that there is often a big difference between ideal and practical.

• A study published in 2017 showed some very negative effects of intermittent fasting when the feeding window began late in the morning (skipping breakfast): increased insulin resistance, higher blood sugar and insulin levels after eating that first meal of the day, an increase in risk of Type 2 Diabetes and cardiovascular disease. Not good!
• With other studies that looked at a time-restricted feeding window that began shortly after waking up, these results were reversed. However, there have been many studies conducted on the health benefits of sleep, exercise and stress management and the positive effects of eating from early morning until mid-afternoon and then fasting until the next morning, were far less significant than the positive effects of these other healthy lifestyle behaviors.
• There are studies showing metabolic benefits of eating breakfast as well as eating in time with your circadian rhythms. Both of these strategies should be easier to follow than some of the intermittent fasting protocols.

• Add extra collagen and cream (almond, coconut, etc.) to your coffee. You could also make bulletproof coffee with butter and MCT oil. Those recipes usually yield about 300 calories.
• Eat a hearty lunch that is easy to prepare: eggs over a great big salad with nuts, avocado, healthy dressing and lots of veggies would provide plenty of nutrition and calories.
• Make dinner as usual for your family and just keep your portion small.
• Stop eating right after dinner. No snacking. At most, have herbal tea.