Twitter CEO Jack Dorsey takes daily ice baths. (Spoiler alert: Ice baths kind of suck.) He uses a near-infrared bulb at his desk. And some time between 6.30 and 9.30 p.m he eats his only meal of the day, one that typically includes "fish, chicken, or steak with a salad, spinach, asparagus or Brussels sprouts."

Why? Dorsey says his one meal a day (OMAD) eating regimen lets him "feel so much more focused." (For the next 22 hours would feel more focused too, if only on my hunger.) 

What Dorsey does is a hyper version of intermittent fasting, an increasingly popular eating regimen that many people say helps them lose weight, reduce inflammation, improve mental acuity... 

But most of those people take a less severe approach to intermittent fasting.

What is Intermittent Fasting?

For starters, think of your body as being in two states: The "fed" state and the "fasted" state.

The fed state takes place when you digest and process food. Once you start eating your body automatically shifts into the fed state. And even after you've finished eating, you stay in the fed state for roughly three to five hours (depending on what you've eaten, how frequently you've eaten, your metabolic rate, and other factors.)

When you're in the fed state, your insulin levels naturally increase, and when your insulin levels are high you typically don't burn fat for energy. Your body doesn't need to tap into its fat stores because what you've eaten gives it plenty to work with.

Eventually, after somewhere between three and five hours, your body stops processing its last meal. There's nothing left to absorb. Insulin levels naturally decrease. 

Somewhere between eight and 12 hours after your last meal, your body enters the fasted state and starts burning stored fat.

When you're in the fed state, your body doesn't need to burn fat. It's like the door to the fat store is locked. When you're in the fasted state, the door to the fat store swings open -- but it takes eight to 12 hours for your body to enter the fasted state.

Start your day with breakfast at 7 a.m., eat another couple of meals during the day, have a 10 p.m. snack... and you basically never go into a fasted state.

Fast for 16 hours, though, and you will.

And that's how, over time, you can lose a few percentage points of fat even if you don't change your exercise routine and don't change what you eat. Keep all the other variables consistent and intermittent fasting should cause you to lose fat.

Science says so; in one study, after eight weeks participants who followed an intermittent fasting eating schedule lost 3.5 pounds of fat while those who similarly exercised and took in the same total calories did not. In another study, participants reduced their waist circumference by 4 to 7 percent. Other studies have shown that fasting can reduce the risk of cardiovascular disease and cancer.

And don't ignore the Jackman science: To play Wolverine in the X-Men movies, Hugh followed an intermittent fasting eating regimen to put on 25 to 30 pounds of muscle -- while  getting ripped in the process. (Although intermittent fasting isn't the only thing he did, it was the basis of his eating regimen.)

That's how intermittent fasting works.

So what if you decide to try an intermittent fasting eating regimen... but don't want to go full Dorsey?

Create Your Intermittent Fasting Plan

The beauty of intermittent fasting is that there really is just one rule: Eat for 8 hours; don't eat for 16 hours. (Some people choose to fast for 18 hours; try it if you want, but, jeez, that's a long time to go without eating.) When you decide to start eating is up to you. What you eat during that time frame is up to you.

Figure out what works best for your schedule and your lifestyle.

Most people wait a while after they wake up to start eating; for me, it's easier to hold off for a few hours in the morning than it is to go, say, from 3 or 4 p.m. until bedtime without eating. Plus, if you work out in the morning before you eat, you get to double-dip on fat burning since your body will use even more of your stored fat for energy.

For most that means eating fewer times during the day. Before I tried intermittent fasting I typically ate six or seven small meals per day. If you're not trying to lose weight, you may have to eat a little more than normal at each meal. (If you are trying to lose weight, intermittent fasting may help you consume fewer calories simply because your "eating window" is smaller. Win-win.)

At first it won't be easy to switch over to a new eating regimen. Consider easing into it. Start out on a M-W-F plan, intermittently fasting on Mondays, Wednesdays, and Fridays and eating normally on the other days. Then, after a couple of weeks, add in another intermittent fasting day, and then another ...

Plus, keep in mind you don't have to go all-in on intermittent fasting. Dick Costolo, an ex-Twitter CEO, takes Sundays off. Other people take a day off every two weeks or so. Some never go past a M-W-F schedule.

Research shows that some of the benefits of intermittent fasting still result from a more limited approach.

But whatever you do, create a plan -- and stick to that plan. Don't fast when you feel like it. Make a plan and follow your plan.

But you don't have to be a slave to it; if you fall off the intermittent fasting wagon one day, just jump back on the next day.

If you do your best but can "only" stick to your plan 95 percent of the time, don't beat yourself up. Ninety-five percent is great. And so might the benefits you'll see.

Or not -- some people don't feel they benefit from intermittent fasting. And that's okay. What you eat, how you eat -- just like what time you get up and start your day -- should work for you.

Life isn't one size fits all.

And neither is intermittent fasting.