What the heck is intermittent fasting, does skipping breakfast slow your metabolism and my experience with the 16/8 intermittent fasting approach.
What if WHEN you eat is just as important as WHAT you eat?
That’s the idea behind intermittent fasting (IF), an eating strategy that carefully regulates the time between your meals to optimize your body for better health. Whether you’re looking to lose weight or just want more mindfulness about your relationship with food, intermittent fasting is something many health professionals are promoting saying that it can boost your metabolism and leave you lighter, fitter, and possibly less prone to disease.
Essentially, IF is the idea that optimizing the timing of your meals throughout the day can benefit your body. By controlling the time that your body spends in “fed” and “fasted” states, you can push your metabolism to its full potential and burn calories more efficiently than before.
When you eat a meal, your body enters a post-absorptive state for three to four hours where it doesn’t burn many calories. Afterwards, it enters a fasted state for eight to twelve hours where it is low on glucose and burns stored fat instead. Since we usually eat meals closer together than that, our bodies don’t spend much time in this fasted state. To fix this, intermittent fasting lets you optimize your meal times so that you spend more time in this prime calorie burning state.
The idea might be new to you, but fasting has been a popular eating strategy throughout history, especially as a religious practice. Intermittent fasting also replicates the way our hunter-gather ancestors used to eat and there are a ton of benefits including:
IF usually has the added benefit of cutting down your daily calorie counts (so long as you don’t overindulge during the eating periods). If you’re over consuming calories regularly, using the intermittent fasting method might be an easy way to cut back. And because of how it revs up your metabolism, intermittent fasting often makes sense for people who hit a plateau in their weight loss journey.
So how does one start incorporating intermittent fasting? Below are four common intermittent fasting techniques.
As one of the most popular (and relatively simple) fasting methods, the 16/8 method where you eat for eight hours a day and then fast for the next sixteen. While you can adjust the timing to whatever best fits your schedule, most people find that a 12PM-8PM eating period works best, so that they fast through the night (mostly while sleeping) and early morning. This plan works best if followed every day, but you can adjust your frequency if necessary.
Of course, the first thing most people ask is doesn’t skipping breakfast (or fasting) decrease your metabolism? And the answer is no. Studies show that as long as you’re not in a severe calorie deficient, your metabolism (or resting energy expenditure I talked about this a little bit in my recent post about eating 3 meals instead of 6 mini meals.
If you specifically want to fast for weight loss, Up Day Down Day fasting might make sense. Essentially, you alternate each day between your regular diet and a fifth of your regular calories (for example: 2,000 and 400). You can follow this strategy until you hit your goal weight or keep going indefinitely. The thought of only eating that little every day doesn’t appeal to me at all so I haven’t tried this method nor would I recommend it.
If you want a low-commitment form of fasting, the 5:2 diet might work for you. You eat like normal for five days a week and cut down to about 500 calories on two non-consecutive days (for instance, a Monday and a Thursday). This is another option I’m not willing to try because I don’t want to limit my calories to 500 for two days a week. I feel like this approach would feel restrictive. It also seems really easy to fall into the habit of overindulging on regular days because you’re depriving yourself for two days a week.
Similar to the 5:2 plan, Eat-Stop-Eat lets you eat your regular diet for five days a week, but you entirely forgo all food for the other one or two non-consecutive days (zero-calorie drinks are okay). This might work for some (especially if the 16/8 method isn’t working) but again it’s not an approach I’ve tried because I don’t like the idea of fasting for a full day.
After hearing so much about IF around the health and fitness world lately I decided I would give it a try. As a health coach/trainer, I find it interesting to learn about different eating styles so incorporating IF into my lifestyle was a fun experiment. As I mentioned above, the only IF method that appealed to me was the 16/8 method so that’s the one I personally experimented with. I tried this eating style for about 6 weeks and only really stopped because of our trip to Israel. The food in Israel is amazing — especially breakfast — and I wanted to fully enjoy myself so I didn’t adhere to the 16/8 method during our travels and I haven’t fully embraced it again since we’ve been back.
That said, I’ve been eager to share some of the things I’ve learned about IF through my experience:
I’m not usually hungry as soon as I wake up // It’s funny because growing up my mom used to joke that I was always hungry as soon as my feet hit the ground in the morning… and this has been true for quite sometime. But over the last few years as I’ve started eating more intuitively and really paying attention to my hunger cues I realized that my desire to eat breakfast as soon I woke up was really out of habit rather than true hunger. Even before learning about IF my breakfast had started moving later and later in the morning and some days I wasn’t hungry for my first meal until around 11:30-12:00PM, which is right on par with the 16/8 fasting approach.
Working out in a fasted state works for me // Working out in the mornings in a fasted state works great for me. I feel strong, energized and focused.
Better Meals + Less Snacking // While following IF my eating schedule looked like this: 12:00 (break the fast with breakfast or lunch, most of the time I had a big salad) 3:00 (lunch #2, usually leftovers, a smoothie, protein bar or something else quick and easy) 7:00 (dinner). Overall, I feel like I was having larger meals that really kept me full, I was eating more veggies (especially for the first meal of the day) and I wasn’t snacking as much. I pretty much cut out after-dinner snacking entirely, which ended up being easier than I thought.
Less Nighttime Eating // This goes hand and hand with less snacking, but I think it’s important to note on its own because I know many people struggle with nighttime eating and IF definitely helps nix this. Nighttime eaters are eating out of boredom or habit (not hunger) or eating because they didn’t eat enough during the day so they’re ravenous at night. Either way, IF gets you in a routine of eating your main meals within the 8 hour feeding window and cutting out the nighttime eating.
Reliance on Coffee // Most people say that having up to 50 calories during your fast doesn’t break it so this means you can have BCAAS, tea or black coffee (or coffee with a little almond milk) during your fasting period. I love coffee and I’m okay with it, but at times during my IF experiment I felt like I was leaning on it a little too much to get through my fasts — not only did it give me something to consume during my fast, but it’s also an appetite suppressant so it helped me get to noon each day without eating. I normally had 1-2 cups each morning (which really isn’t too much) but it’s something I wanted to mention because although coffee is said to be fine during your fast, it’s been shown to increase cortisol (stress hormone) levels which can lead to weight gain and fat storage, especially around the tummy). It’s also important to note that fasting itself can increase cortisol levels too and the adverse affects of higher cortisol levels could easily counter-balance all the benefits of IF.
Scheduling Could be Tricky // The hardest part of IF was definitely being finished eating by 8PM each night. Before my IF experiment Isaac and I were eating dinner around 8:30 or 9:00PM so moving dinner up was kind of difficult. There were days where Isaac would get home from work at like 7:50 and be like, “Oh shoot, you have 10 minutes to eat dinner.” I was never super strict about the eating window so this was really a joke, but this just shows that sometimes this part of IF can be tricky. That said, you can always tweak your eating window if needed. For instance, if you have dinner with friends one night at 8PM, you could start eating for the day at 1PM so your window could last until 9PM.
Hormonal Issues // I was a little worried about trying IF since I’ve dealt with hypothalamic amenorrhea in the past and there is some research that fasting can affect women differently than men. This article does a great job sharing all the research. I didn’t see any of these negative side effects during my experiment and my period stayed consistent, but I was fully prepared to stop fasting if my cycle was affected or if I was experiencing any adverse affects.
Results // I felt really good following the 16/8 eating style for my six week experiment. I didn’t lose any weight, but I am totally fine with that because my current goal is to build muscle and lose fat, not necessarily change the number on the scale.
At this point I’m not sure if I’ll go back to following the 16/8 IF eating style. I do think there are some benefits to IF and it can definitely be a helpful tool for some (i.e. someone going through a weight loss plateau), but as with most things health and fitness related I gravitate toward a more moderate, balanced approach. If someone is just starting out with their weight loss journey I’d have a slew of basic healthy habits that I’d help them incorporate first before trying something like this.
Moving forward my plan is to stick with a moderate approach of eating breakfast whenever I start to feel hungry in the morning (usually around 10:30 or 11AM) along with finishing dinner at a early-ish hour (7:30-8PM). This way I won’t be going to bed on a full stomach so I’ll still able to give my body a long break from the stress of digestion and some time to burn fat, but I don’t have to worry about following the specific 12-8PM window. For me, this will likely mean that my average fast is about 12-15 hours and I’m okay with that!
Have you tried intermittent fasting before? I’d love to hear about your experience, so feel free to share it in the comments below.