Thursday, August 28th:
I feel good. This surprises me since I just ate my first food of the day. Given that by any normal 9:47am, I’ve already scarfed down several hundred, if not a thousand, calories, I’m impressed.
It’s all part of my intermittent fasting experiment. The strategy I’m going to use is a 14 to 16 hour fast (some recommend up to 18 hours, with diminishing returns for women as you get into the 14 hour and longer range) daily. This means that last night I finished dinner at 7pm – and didn’t eat today until almost 10am, just shy of 15 hours.
I’ve been hesitant to try this dietary strategy that research has shown helps you lose body fat, gain muscle, feel energized and live a longer life. I’ve seen reputable nutritionists stand behind it. My fear was that I’d lose energy for long workouts, especially important when training for ironman, but when I finally sat down, crunched some time numbers and put together a schedule – it doesn’t really seem all that bad.
Intermittent fasting can mean many things. A weekly full-day fast, a bi-weekly full-day fast or a daily fast of more than 12 hours (usually the 16 to 18 hours) are all options. As I mentioned above, I’m going for that final option. It’s said that true fasting doesn’t occur until 12 hours have passed, which is why you can’t just skip a snack and reap the benefits.
For my experiment, I’ll feed for 8 hours (not straight, that’s just when you can eat) and fast for 14 to 16, depending on the day’s circumstances. I’ll plan my last meal on most days to happen at 4pm and begin eating again at 8am. Some days I might push the last meal back a bit and the early meal up, shortening the fasting window – say in case of a race or a long workout.
You can set really any schedule you like. Many people prefer to skip breakfast and fast from 8am until 12 or 1 pm.
A study published in Cell Metabolism in 2012 found that mice fed in just an 8-hour window demonstrated healthier metabolic function and actually lost weight despite consuming the same number of calories as their mouse friends who ate without a restricted window. The other alleged benefits include increased blood flow to fat cells, greater concentrations of epinephrine and norepinephrine (feel good neurotransmitters), slight rise in your metabolic rate, decrease in insulin levels (chronic high levels of insulin mean more calories stored as fat) and more fat used for energy. You’d think I’d have learned after my vegan and paleo experiments that messing with diet can lead to some issues, but the temptation to try is just so great.
So, I coached runners this morning at 5:30 am with a little growl in the tummy, but I often go without food for this session. I wanted breakfast when I returned home, but in reality I had so much to do with getting the kids ready for school and joining my daughter on her short training run, I didn’t really even have the time to notice the missed meal. I dropped them off and headed to the treadmill.
This was the part that worried me – unfed speed intervals. After all, I like to go into most workouts with some fuel in my system. But, I found I felt good –I powered through a one-mile warmup, 4x400s and a one-mile cooldown. No sluggishness in the legs, no bonk. Afterwards, I broke the fast with a ½ cup of cashews and an orange before I went to teach Pilates. Granted the workout wasn’t very long, but it was encouraging. With the schedule I’ve set, I’ll only have to go into an early morning hour-long workout fasted – this proved it was doable.
Up until the 10am (or so) fast break, I felt bright, alert and energized. No foggy mind or even distracted dreaming of food. Granted, it’s day one, but still encouraging.
Remember, fasting isn’t for everyone. If you are prone to low blood sugar, have diabetes, are pregnant or breastfeeding — do not attempt without first speaking with a doctor.
We’ll see what tomorrow brings, but so far, I’m a fan.
For more on Intermittent Fasting and the pros and cons, check this article from Experience Life.