Calorie deficit, OMAD, intermittent fasting: How do they work, and which is best?

From calorie counting to intermittent fasting and the challenging One Meal a Day (OMAD) diet, people looking to lose weight have no shortage of options.

But do these different dieting strategies actually help people achieve that goal, and is any one approach better than the others?

According to experts, while these approaches may seem vastly different, they all boil down to one key principle: creating an energy deficit.

Bernice Sabenicio, RND, resident nutritionist-dietitian at Reshape Slimming & Fitness Club, told GMA News Online, "All approaches can work mainly because they help create an energy deficit. The body loses weight when energy intake is consistently lower than energy expenditure."

Pasig City Nutrition Committee nutritionist-dietician Christian Jay G. Vasquez, RND, echoed the sentiment, saying, "Weight loss is ultimately determined by total calorie intake. The body needs to burn more energy than it receives from food."

Definition of terms

Calorie deficit: This is is when one consumes fewer calories than the body burns, typically by reducing daily intake.

Intermittent fasting: This involves alternating between periods of fasting and eating, with one of the most common methods being the 16:8 approach, where a person fasts for 16 hours and eats within an eight-hour window.

OMAD: This involves limiting food intake to a single meal each day.

Who benefits most?

Calorie deficit: According to Vasquez, this remains the "clinical gold standard" for athletes, individuals with high physical output, and those who prefer predictable, evenly spaced fueling throughout the day.

Intermittent fasting: Individuals with insulin resistance or metabolic syndrome. According to Sabenicio, it may also benefit people who prefer fewer meals or need more structure with their eating schedule.

OMAD: Sedentary individuals or those with extreme time constraints who psychologically prefer consuming one large, highly satisfying meal over multiple small ones, Vasquez said.

Best and worst

Both experts agree that all three could work, but they expressed preference for calorie deficit.

"Calorie deficit has the strongest evidence, but it should still be personalized through assessment by a dietitian because di dahil effective sa isang tao ay gagayahin na ng lahat," Sabenicio said.

As for intermittent fasting, Sabenicio said is "not proven to be better than a regular calorie deficit and is not suitable for everyone." She also discouraged OMAD, calling it an "extreme form of fasting."

"OMAD may increase the risk of nutrient deficiencies because it can be difficult to meet daily needs for macronutrients and micronutrients in one meal. It may also lead to muscle loss, low energy, overeating, constipation, and bad breath," she said.

Vasquez likewise underscored the "high risk of malnutrition" in OMAD.

"A position stand in the Journal of the International Society of Sports Nutrition points out that the human body can only optimize a finite amount of protein for muscle building at one time. Compressing protein intake into a single daily spike limits Muscle Protein Synthesis (MPS), severely risking muscle wasting over time."

What to consider

Before jumping into a new diet, Sabenicio said there are a few important things to consider, starting with one's medical condition.

"Hindi lang weight loss ang pinag-uusapan natin. We need to look at the bigger picture, which is overall health talaga. Baka naman akala mo maganda, pero mas mapasama pa," she said.

Another is lifestyle and schedule, and whether or not you can maintain the plan.

"Can you prepare your food? What about long commutes? Or kung ano ang nakahain, 'yun din kakainin?" she asked.

"The best diet is usually the one a person can consistently follow for months and years."

Sabenicio also highlighted "MOVABA," which stands for moderation, variety, and balance. "Ang goal natin ay magkaroon ng pagkain na adequate sa kailangan ng katawan mo."

Vasquez meanwhile said to keep in mind that dieting is not a "one-size-fits-all" situation.

"You need to understand your body and your habits before implementing a new regimen," he said.

"Second, practice patience. Maintaining a sustainable diet requires long-term patience in order to build lasting food habits that limit the intake of excessive sugar, salt, and fat," he added. —JCB, GMA News