What is Time Restricted Feeding?
It simply means you are going to narrow the window of time within which you eat each day. It is basically the inverse of Intermittent Fasting which is the opposite, indicating the hours of the day you do NOT eat any calories. Generally, this means consuming all your daily calories within an 8 hour window. This does not imply that you eat a perfect diet or even reduce your caloric intake. It simply means having hours of the day that off limits to caloric intake. I will outline what an ideal schedule looks like but you may feel the need to make small adjustments to it based on your family, work and lifestyle needs. With any adjustment it is important to come back and examine, “what are my results?” “Is this working for me?” Stay curious about how your body works and work with it not against it for the best outcome.
Why do it?
The simple truth is that we were built to “fast”, to go without food from time to time in order to keep our cells and our bodily processes sharp and efficient. Modern living gets in the way of that. Things are too easy and so we live a lazy life that doesn't challenge our physiology but instead tortures it with excess. Excess calories perhaps but most definitely excess number of hours where calories are being poured into the body. Periods of fasting allow the body to heal and repair. The digestion of food does provide energy but at a cost. The cost is inflammation and oxidative stress on our cells. The business of digesting food turns on thousands of genes in the liver, pancreas, and gut. Firing up this engine demands a bit of energy expenditure and as you might imagine, it also creates a bit of waste product that needs to be cleared. It is during these fasting periods that our cells are able to clear the waste and stay sharp.
Imagine if you were in the kitchen preparing a meal and you just kept cooking for hours on end without a break. The kitchen would be a mess with tons of dirty dishes, pots and pans, counter top messes and open containers. That kitchen would become less and less efficient at doing the job it was intended for. But if we clean it up and give it a rest, it will be ready to perform later on. Your cells need that same time to clear out junk. The average American eats for 15 to 16 hours a day. First thing upon rising, multiple meals and snacks through the day and often a late snack before bed. There is very little down time. No chance for the gene signals to “reset”. So, the idea of fasting is a simple way to undo some of the damage we have created through modern living.
Benefits of “Restricted Feeding Windows”
Here is what hundreds of studies on this topic have found as the benefits:
• Decreased fat mass and increase in lean muscle mass
• Greater insulin sensitivity, thus reduction of diabetic risk, or reducing diabetes.
• Reduced inflammatory markers, so less joint pain, headaches, and heart disease.
• Improved cholesterol profile, more than a 50% reduction in triglycerides
• Increased mitochondrial volume in liver and brown fat. Mitochondria make energy.
• Increased ketones which are energy units the body uses made from burning fat.
• Protection from fatty liver disease.
• Enhanced endurance in aerobic exercise.
• Improved sleep patterns and deeper sleep.
Gee . . . that sounds a LOT healthier, and it doesn't require you to DIET. Even if you ate the same foods you are currently eating but simply squeezed them into an 8 hour window it would be a great step forward. In one mouse study they fed mice a crappy diet loaded with excess sugar and the mice that were placed in the restricted feeding group were much healthier.
How to do it
Your start point may be to first reduce the hours in which you eat down to 12 hours, and then over a week or two reduce that down to 10 hours, before arriving at the ideal 8 hours window shown below.
Look at the yellow “feeding window” above. Let’s say we ate from 11am to 7pm and took our last bite of food at 6:59pm. That food would be in our gut and the digestive process would continue for another 3 hours. Our true fast wouldn't really start until 10pm as we head to bed. Obviously, we are fasting through the night unless you have a habit of midnight cookie runs, in which case we have bigger issues to address. Let’s say that we arise at 6am, getting 8 hours of luxurious sleep. We awaken with a clear intention to have NO calories until 11am, the opening of our feeding window. Water intake is fine and actually encouraged.
But what about my coffee or tea? This is where the waters get a little murky. By the true definition of fasting even black coffee breaks a fast as it metabolically stimulates the liver to awaken and arise function. It doesn't elevate blood sugar but it does engage the liver in activity which is the definition of a fast. For those not looking to lose weight or reverse diabetes this might in fact be acceptable. I would suggest the following: consume NOTHING but WATER for the first hour that you are awake and then beyond that into your second hour of the day if you choose to take in black coffee or plain tea, simply be certain that this is free of creamer or calories of ANY type. If you add a single calorie your fast just ended.
The Insulin Phenomena
We all function much the same in our base physiology. We make melatonin at night which inhibits insulin from working or even being made. The first hour of the day should ALWAYS remain fasted, otherwise we risk weight gain and diabetes as there is very little insulin to manage the glucose we are ingesting. Both carbohydrate and protein intake stimulate blood sugar to rise. Fat does not. The intake of pure fat without carb or protein doesn't drive a blood sugar response. This opens the door to another exception to the above rule. If after the first hour of fasting I decide that I need calories or want a source of fuel to drive my brain and body then I could add fat to my coffee or tea. I could even consume fat all by itself in the form of M.C.T. oil. The intake of fat is in fact a calorie and does break the fast. This might reduce our overall benefit from Time Restricted Feeding, but we have to weigh this in light of our desired outcome. If you are a diabetic or trying to lose weight, then I would not recommend engaging this option initially. Become a pro at limiting calories to just those 8 hours and document success. See your weight drop, your labs improve and your body change. Once this is firmly established you can play with the concept of adding fat into the morning prior to the 11am start time for feeding. But monitor its impact. Is the perceived benefit worth any drop or change in the progression toward your goal? You won’t know unless you measure so decide what it is you are tracking and be precise. This is not the time for a crap shoot.
Play with this simple concept and get used to the idea of being hungry for a little while. I guarantee you that if you simply relax into the idea and experience your body with an open mind you will find joy inside the notion of fasting. KNOW with certainty that this practice or other fasting practices like it have been shown beyond a shadow of a doubt to be healthy for the human body. These practices are used in clinical medicine to reverse diabetes, reduce heart risk, reduce cancer risk, improve cognition, lose weight, slow the rate of aging and much more. It is simply an easy, FREE tool, that will make you healthier and stronger.
In part 2 of this article I discuss the layering of other strategies such as carb reduction, ketogenic diet, fasted workouts and Zone 2 training. All of these strategies work independently but gain power when combined.