What’s your favorite meal of the day? Maybe it’s breakfast when you can have a hearty plate of eggs and bacon, or dinner when you can finally have that salmon you’ve been thinking about all day.
Now, imagine that’s the only meal you can eat each day. That’s the premise behind the OMAD diet, which stands for “one meal a day,” which is essentially a form of fasting.
While fasting can be good for you (just ask Vanessa Hudgens or Jenna Jameson), some experts believe certain methods like the OMAD diet aren’t a healthy, sustainable solution for weight loss. Here’s what you need to know.
What exactly is the OMAD diet?
“Think of OMAD as intermittent fasting on steroids” says Dena Champion, R.D., of The Ohio State University Wexner Medical Center. “OMAD is literally when someone eats one meal daily during one hour of the day and then fasts the other 23 hours.” You are allowed to drink black coffee or other non-calorie drinks during that fasting time—but nothing else.
On top of that, you’re instructed to eat that one meal during the same four-hour window every day, says Jen Oikarinen, a clinical dietitian with Banner University Medical Center Phoenix. “Consistency is emphasized in the OMAD diet,” she says. And while it is recommended that you make healthy food choices, it’s more about when you eat than what you eat, says Champion.
OMAD dieters are supposed to adhere to a set of rules known as the “4 ones,” says Oikarinen. So if you’re on the OMAD diet:
Worth noting: While the OMAD diet is technically a fasting diet, it’s quite different from other intermittent fasting diets like the 16:8 diet, which instructs you to fast for 16 hours and eat three (or four!) meals during the remaining eight hours.
So, can the OMAD diet help me lose weight?
Yes, but again, some experts say it’s neither healthy nor sustainable weight loss.
OMAD is basically a starvation diet, if you follow all the stipulations, says Rebecca Elbaum, R.D., clinical administrative dietitian at Montefiore Medical Center in New York. That’s because you’re not consuming enough calories with just one meal as you would by eating eating three or four times a day, so weight loss will occur,
Also, because you’re eating so little (and so sparingly), you’d also likely go into ketosis (the state during which your body burns fat for fuel instead of carbs) from this diet—not because you’re upping your fat content and decreasing your carbs, but because you’re eating very little in general, says Elbaum.
Aside from the weight loss, a fasting program like OMAD can also result in mood swings, muscle loss, hormone disturbances, and even changes in your menstrual cycle (like having it stop completely), says Oikarinen. “Another major concern is the increased risk for nutrient deficiencies; decreased intake of food also means decreased intake of beneficial vitamins and minerals,” Oikarinen says.
Should I try the OMAD diet?
While plenty of people sing the OMAD diet’s praises online, and some experts certainly endorse various forms of intermittent fasting, Elbaum believes not even healthy people should try the OMAD diet. And that goes doubly for anyone who’s pregnant, breastfeeding, recovering from past disordered eating, has diabetes, or even regularly exercises or lifts weights, she says.
“Healthy weight loss will be whatever is the most sustainable over a lifetime,” she says. “This includes a healthy, balanced diet and regular exercise.”
If you are interested in some type of fasting, a less intense form (like the 16:8 diet) might be your best bet—but even then, it’s wise to talk to an R.D. about your options and how best to work an intermittent fasting diet into your lifestyle, says Oikarinen.
The bottom line: Definitely steer clear of the OMAD diet—it won’t promote healthy or sustainable weight loss.