When you eat may be just as important as what you eat. How to use fasting to support a healthy weight management plan can be confusing.
Here’s some more context to help you…
One of my favorite strategies to jumpstart weight loss is by keeping all calories inside a set window of time.
The strategy is called time-restricted feeding or intermittent fasting. And, trust me, it can change your life.
Time-restricted feeding is when you keep all calorie intake within a set window of time versus eating throughout most of the day (12+ hours).
A recent study published in the Journal of the American Medical Association looked at weight loss and other health measures in two groups of people with obesity.
Both groups received weight-loss counseling and the same calorie reduction and exercise instructions over 14 weeks. The only thing that changed was the window of time they were instructed to eat in the day.
The first group kept all eating within the time window of 7 AM and 3 PM (8 total hours). The second group ate over 12 or more hours (for example 7 AM to 7 PM or later).
At the end of the study, both groups lost weight.
Yet, the time-restricted feeding group who kept all calories between 7 AM and 3 PM lost almost 50% more (~15lbs vs. ~10lbs)!
Blood pressure was also slightly lower in the 8-hour eating group.
When Should You Fast?
Most Americans fall in the category of eating and snacking throughout the entire day.
Keeping eating to 12 hours a day I think is a great strategy to shoot for at a baseline. Most fasting schedules look at 14-16+ hours.
Our physiology is thousands of years old, and for much of human history, we did not have ready sources of food available 24 hours a day. It could be normal to go a few days with just a handful of calories, eventually getting a score like a beehive full of honey or a hunting kill that would feed for a week.
By not engaging some of these primal systems, we’re not fully eliciting all of the protective systems available to our body.
Intermittent fasting is one way to get the most out of the modern world while honoring the physiological conditions of our ancestors.
Intermittent fasting for 14-16 hours is one of my favorite diet hacks, yet there are some exceptions when fasting for longer than 12 hours may not be right for you…
- If you’re stressed or burnt out, intermittent fasting is probably not the first strategy to try. When you are fasting, your stress hormones kick in to raise your blood sugar and keep it at normal levels. So if you’re stress hormones are overworked or very depleted, fasting is not the best first-line strategy for you.
- Women can respond differently to fasting. Women have hormonal changes related to their menstrual cycle that can put extra demands on their stress hormones. Because of this, women during the week of their cycle may want to shorten their fasting time. Moreover, If you have a history of irregular menstrual cycles or moderate to severe PMS symptoms, you may want to ease into a fasting strategy all the same and see how your system responds. The metabolic benefits will circle back to help support hormonal rhythms, but let your body be your guide.
- Those with moderate to high physical activity or training may have different needs, especially post-workout depending on fitness goals. It can be more difficult to fit all the recovery calories they may need if trying to build muscle or fuel long-distance training. Overtraining can disrupt hormonal rhythms in both men and women, leading to burnout, and this can be common in weekend warriors, CrossFit members, and those training for endurance events.
- A person with a history of an eating disorder should tread very carefully when considering any fasting protocol. Instead, following the path of regaining a healthy relationship with food that is very personalized is a priority. My clients who fit this profile have been very comfortable reporting their experiences and are self-aware of tendencies – but I acknowledge those who also quietly struggle.
There are other strategies to explore well before intermittent fasting should ever be considered as a strategy. Seeing a tendency toward eating behavior as something separate from our identity is a powerful and necessary start to redirect our behavior.
As soon as you “label” a behavior, it is now something outside of the “I” in your head, and you can start to identify when that separate part of you is activated.
Once identified and noticed, you can learn how to immediately trigger replacement behaviors that serve greater values, purpose, and fulfillment.
This means identifying the environments and relationships in your life that trigger those behaviors, and incrementally taking steps to “trade up” in those worlds.
Your internal identity is then slowly rewarded by further validating that increasing sense of joy and fulfillment, and the separate part of you that is not serving you can be slowly shrugged away, versus wrestled away.
When you “wrestle” with something, you validate it. The better approach is to notice the other side and learn to say to yourself, “Thank you, but not needed”.
For those that do qualify for intermittent fasting, the strategy is about keeping ALL calories (food and drink) within a 12-hour window or less, with more benefits when eating windows are kept to 8-10 hours. This means that fasting 12-16 hours a day, with occasional 24-hour fasts, may be preferred for maintaining a healthy weight, even when calories and exercise levels remain the same.
Coffee and Intermittent Fasting
One of the top questions that comes up is “What about my morning coffee?”.
Black coffee or plain tea can be okay while fasting, but once you add cream or sugar, it breaks your fast.
Some stricter advocates for intermittent fasting say that caffeine will still bring about hormonal responses (including raising your fasting blood sugar) and that you should preferably stay caffeine-free.
The same might go for zero-calorie sweeteners like stevia, monk fruit, sucralose, aspartame, and others that while having no caloric value – may still trick the body and elicit hormonal responses as though you did consume calories.
So if you want to be strict and get the most out of the strategy, make sure you limit all caffeine and non-calorie sweeteners when fasting too.
Yet, I will be clear that you can still get results while enjoying your coffee and tea – just plain with nothing added.
I will also say that coffee is physiologically addictive and habit-forming, and it physically changes how your brain and body respond to fatigue and stress. As a result, you can feel fatigued, stressed, and have trouble focusing at a baseline – and this is a sign your body is physiologically dependent on caffeine and it’s time to take a break.
To prevent this, ideally, you should take periodic breaks such as 30 days on, and 14 days off, to allow time for your brain receptors to recover. When fasting, your physical and mental energy stays much more balanced throughout the day, and you will feel less of a “need” for that caffeine boost in the morning or afternoon.
If you “NEED” your coffee, it might be time for that 14-day caffeine fast!
What to Expect with Time-Restricted Eating
You’ll find that while the first 1-3 days you may feel pretty hungry in the last 1-3 hours of your fast, by the 3rd day or earlier, your hunger and satiety hormones will naturally reset.
You’ll find you have to remind yourself that you can eat because you feel clear-headed with good energy without the normal roller coaster ride of spikes and crashes of sugar, insulin, and hunger-related hormones.
This alone can supercharge your life – when you’re not being controlled by your hunger hormones, your presence with your family, your productivity at work, and your willingness to take care of your body all will improve – and the strategy becomes self-motivating and self-fulfilling.
So give it at least three days before throwing in the towel, and if you mess up, don’t kick yourself, you can always start with a 12-hour fast and gradually increase it by 15 minutes until you get to the ideal 8-hour eating window.
If you’re under more stress or starting your menstrual cycle, give yourself some more wiggle room but try to keep to 12 hours fasting time at a minimum. If you’re extremely active, make sure you are recovering with enough calories in your eating windows too!
All you have to do is look at the time when you finish your last meal or snack of the day and tack on 12-16 hours to know when you can start eating anything with calories again.
While the JAMA study looked at early time-restricted feeding (eating only between 7 AM-3 PM), I like to eat between 11 AM and 7 PM because I can fully take advantage of sleeping hours without feeling hungry when I’m trying to fall asleep.
Finishing at 7 PM also allows a window where the food in my stomach is not going to mess with my sleep quality – which is another secondary benefit of fasting.
Weight loss and metabolic efficiency in processing your food are just a few of the benefits offered by time-restricted feeding.
Intermittent fasting goes beyond shedding pounds; it significantly impacts gut health by enhancing the diversity of gut bacteria. This allows your digestive system to thoroughly process food, breaking down components into prebiotic compounds that nourish your gut.
When following intermittent fasting correctly, you’ll find that your metabolic responses to the same foods will be 20%+ better the next day as your digestive system is primed to efficiently process your food without the normal strain of American diets.
You’ll find yourself feeling less bloated and experiencing more regular bowels. Your immune system will be less reactive as well – so food tolerance can improve. Otherwise eating constantly can have immune responses build on one another where your baseline state is just inflamed, achy, reactive, and uncomfortable.
Mental fog can dissipate. Mood swings go away. Skin can look and feel better. Joints can feel less stiff and achy. And, as mentioned in the last section, you’ll fall asleep easier, and enjoy better sleep quality.
Of course, the experiences described in the study and the potential benefits can vary among individuals, and what’s right for you will differ depending on your health history and starting point.
Feel free to allow a cheat day a week, but you’ll notice that your fast will be tougher the next day, and it will take 1 to 3 days to normalize again. This realization of how you feel during and after a cheat day will become clear proof to you of how well the fasting strategy is working for you.
When you have extra carbohydrates, understand that your body will hold on to extra water weight too, it is not abnormal to be 5lbs heavier the day after a cheat day. This can also take 1-3 days to normalize – so be careful of daily weighing on the scale without taking into account the last 3 days!
Autophagy, Zombie Cells, and Fasting
The other thing that happens at about 14-16 hours of fasting, is that the body starts to eat up old, unneeded cells and clean up damaged proteins – a process known as autophagy.
“Auto” means self. “Phagy” means to eat. Autophagy is the body’s process of eating up old cells that have served their purpose and stopped functioning – yet stick around spitting out free radicals and causing inflammation in the body.
These “zombie cells” build up over time and contribute to aging.
The body has a clean-up crew that eats up these old cells so that things are fresh and ready for the next day’s activities.
This cellular clean-up is increasingly recognized as an important anti-aging strategy and an exciting benefit beyond weight loss that you’ll enjoy when you commit to this strategy.
The best way to trigger autophagy? It is by fasting for 14+ hours, the longer the fast, the better the clean-up. 24-hour fasts really maximize the benefits of autophagy without starting to eat into muscle tissues and cells you want to keep.
Yet, one might also supercharge this cellular clean-up by taking proteolytic enzymes and isoquercetin that go beyond our discussion here yet are worth mentioning. In short, they help speed up that cellular clean-up and you can get more out of your fast without going as aggressive as 24-72 hours.
Periodic episodes of longer fasting will also accelerate this cellular clean-up but are not for everyone as they range from 24-72 hours, to aggressive as a fasting-mimicking diet of 5 days with some allowed calories.
Adding salt to your water can also help extend your ability to fast if you find yourself getting dizzy when standing up, foggy-headed, or generally feeling a slump. I keep a pinch bowl of salt on my counter not just for cooking, but to add to my water easily.
Give Intermittent Fasting a Try
Controlling when you eat, may just be the lifestyle change you keep this year.
The power of time-restricted feeding and intermittent fasting to supercharge your weight loss and overall well-being cannot be underestimated. It’s not just about what you eat; it’s also about when you eat.
As demonstrated in the small JAMA study mentioned above, the game-changer was the time window within which they consumed their daily meals. I hope that the added discussion on gut and anti-aging benefits adds more fuel to the fire – just give it at least three days to start noticing the benefits.