A guy in my Skool community messaged me asking if he should switch from 16:8 to OMAD because a YouTuber said it burns fat faster, and I realized most intermittent fasting content answers that question with vibes instead of the actual research comparing the methods.
Intermittent fasting is any eating pattern built around a time window rather than around what you eat, and the main methods are 16:8 (eat within 8 hours), 5:2 (eat normally 5 days, restrict to 500-600 calories on 2), alternate day fasting, and OMAD, one meal a day. Research comparing them shows they all produce similar fat loss when total calories are matched; the method that works best for you is the one you can actually stick with for months, not the one with the most dramatic name. 16:8 has the highest long-term adherence of the group, which is exactly why it’s the one I default to and the one built into the Holy Diet inside Project Kingdom Gladiator.
The Main Intermittent Fasting Methods, Compared
Every method below does the same basic thing: it compresses your eating into a shorter window so your body spends more hours in a fasted state. What changes is how extreme the window gets.
16:8 means an 8-hour eating window, typically noon to 8pm, with the other 16 hours fasted. Since sleep covers 7-8 of those hours, you’re only consciously fasting for around 8 waking hours, which is why beginners tolerate it well.
18:6 and 20:4 push the window tighter, down to 6 or 4 hours of eating a day. These require more discipline but produce a deeper fasted state.
5:2 keeps five days normal and restricts the other two to 500-600 calories, giving you the metabolic benefit without fasting most of the week.
Alternate day fasting (ADF) cycles a very low-calorie day with a normal-eating day, every other day, which is effective but hard to sustain long term.
OMAD compresses everything into one meal a day, roughly a 23-hour fast. It’s the most intense version and tends to have the lowest long-term adherence of the group, around half of people still doing it after a year, compared to closer to 80% for 16:8.
Does the Method Actually Matter, or Just the Calories?
Mostly just the calories, and I’ve written about the full research comparing fasting to standard calorie restriction here. What changes between methods isn’t fat-loss magic, it’s how easy each one is to actually follow.
16:8 wins on adherence because it barely disrupts your day: you skip breakfast, eat lunch and dinner, done. OMAD and ADF can produce faster short-term results for people who can stick with them, but most people can’t, and a perfect protocol you quit in three weeks loses to an imperfect one you’re still doing in a year.
Pick the tightest window you can actually sustain, not the one that sounds most impressive. Protocol-hopping, switching from 16:8 to OMAD to 5:2 every time a new video promises faster results, resets your adaptation every time and usually ends with someone quitting fasting altogether out of frustration. Pick one, run it for at least a month, and only change it if it’s genuinely not working, not because something newer showed up in your feed.
Does Intermittent Fasting Kill Your Metabolism?
No, and this myth won’t die. The “starvation mode” fear comes from studies on prolonged, severe calorie restriction, not from 16-24 hour fasting windows.
Short fasts don’t trigger that response. Some research actually shows a short-term metabolic increase during fasting, driven by a rise in norepinephrine, not a slowdown.
The related myth, that skipping breakfast wrecks your metabolism or your focus, traces back to a 1917 Kellogg’s cereal marketing campaign, not a body of science. Modern trials find no consistent weight or cognitive advantage to eating breakfast over skipping it.
What About Muscle? The Honest Answer
This is the question I get most from men trying to build muscle on the Arc Blueprint or Samson Strength phases of PKG, and it deserves a straight answer instead of a hand wave.
Some researchers genuinely worry that compressing meals into one or two feedings a day gives you fewer windows to trigger muscle protein synthesis compared to spreading protein across four or five meals. That’s a real, reasonable concern, not a fringe take.
But when researchers actually tested it, a 12-week study combining intermittent fasting with resistance training found lean body mass increased just as much as it did with standard calorie restriction, as long as training and protein intake were both solid. The practical fix: aim for 30+ grams of protein per meal, and don’t let your training session sit too many hours away from your next meal.
Fasting doesn’t cost you muscle. Skipping the training and the protein while fasting does.
In practice, that means lifting near the end of your fasting window, right before your first meal, so you’re refueling immediately after the hardest stimulus. If you train fasted at 6am and don’t eat until noon, you’re leaving your muscles waiting six hours for the amino acids they need to actually rebuild.
Is Intermittent Fasting Different for Women?
Yes, more than most fasting content admits, and this matters since a fifth of the people in this program are women or wives fasting alongside their husbands.
Estrogen, progesterone, cortisol, and thyroid hormones all shift across the menstrual cycle, and all of them respond to how much food is available and when. Research on women specifically suggests the follicular phase, roughly the first two weeks after your period starts, tolerates longer fasting windows well, while the luteal phase, the two weeks before your next period, often needs shorter fasts and more consistent food to avoid disrupting ovulation or spiking cortisol.
Interestingly, in women with PCOS specifically, structured fasting protocols improved insulin sensitivity and normalized menstrual cycles in a third to 40% of participants studied. The takeaway isn’t “women shouldn’t fast.” It’s that a rigid, one-size-fits-all window is more likely to backfire for women than for men, and adjusting the fast to your cycle beats forcing the same schedule every week.
A common practical adjustment is “crescendo fasting”: fasting on non-consecutive days, say Monday, Wednesday, and Friday, instead of daily, which gives your hormones more recovery time between fasts while still delivering most of the benefit.
Where This Actually Fits Into the Holy Diet
Project Kingdom Gladiator doesn’t ask you to pick a trendy protocol off a list. The Holy Diet uses a simple version of 16:8 daily, eating until noon or 1pm, plus one weekly 24-hour fast, and that’s it.
No OMAD, no alternate-day cycling, nothing that requires a spreadsheet to track. It’s the version with the highest real-world adherence, built for people with a 9-to-5 and a family, not for someone whose full-time job is optimizing their eating window.
If you want the deeper biblical case for why fasting matters beyond the metabolic angle, that’s covered here, and if you need the exact mechanics of starting your first fast, the step-by-step guide is here.
I’m a personal trainer, certified since 2011, and I’ve run this exact 16:8-plus-weekly-fast pattern on myself for years before ever putting it in a program. You can read more about my story at tylerinloes.com/about.
Stop chasing the protocol with the most extreme name. Pick the one you’ll still be doing a year from now, and let consistency do what no amount of intensity ever will.
