With every flip of the calendar, it seems a new diet fad captures national attention, promising effortless weight loss. The Paleo diet is how our ancestors ate – it must be healthy. No, try intermittent fasting. Scratch that – this prune juice detox will take inches off your waist in days!
Prof. David Levitsky, nutritional sciences, describes obesity as the “biggest public health problem we have.” Its cause? Not carbohydrates or processed sugars as the latest trend might have you believe. The science behind obesity is simple: excess calorie intake.
“The fundamental science behind nutrition and related physiology has not changed for decades”, Levitsky said. Instead, it’s the media, with a motive to sell, writing about the science that changes. While some diets make it easier to consume less, they may be unnecessary.
With this perspective on nutrition, the vegan diet may be the healthiest of them all. “Vegans live longer than anyone else,” Levitsky said. “That should tell you something.”
“But it’s not the meat that’s going to kill you,” Levitsky explained. There is no magical quality of plant-based diets that will make you immortal. Vegan diets drastically improve health outcomes “because, on average, they’re far lower in dietary fats compared to omnivorous diets and higher in fiber.”
But despite the benefits it carries, Levitsky also urged caution towards vegan diets. Since vegan meals often don’t contain complete proteins and are low in iron, vegans “need to be very cognizant” in planning their meals and combining appropriate protein sources.
Some of the most popular modern diets — Paleo, Atkins and Keto, to name a few — portray carbohydrates as the antithesis of health, a macronutrient to be avoided at all costs.
Carbohydrates don’t deserve this reputation, Levitsky said. Like any other macronutrients, the problem is overconsumption, and carbs are the easiest to overeat, as we “typically eat 60-65% of our calories from carbohydrates.”
In a low-carb diet, that range drops to 10-15%, Levitsky said. He explained that this doesn’t discount low carb diets’ efficacy for weight loss, but there are a few issues if one endures a low-carb diet.
First, the rapid drop in weight may not be from fat tissue, but instead from fluids. Excess carbohydrates are stored in the body as glycogen, which holds large amounts of water with it. As low-carb diets deplete these stores, the water rapidly flushes out.
“The other problem is the fact that people can’t stay on low-carb diets for long periods of time. If you look at the population statistics, most people can’t stick to these for more than a few months.” Levitsky said. “And once you start indulging in those pre-meal bread rolls again, you’re just going to put [the weight] back on immediately.”
Ultimately, low-carb diets are “not an effective way to lose weight and sustain it,” Levitsky said.
A number of other fasting schemes have gained popularity recently, but the idea behind them is the same: limit the period of time during which you eat.
Levitsky describes these methods as “very effective for losing weight,” but emphasizes that there is no special benefit of eating only during specified windows. “These are simple mechanisms to reduce caloric intake.”
“It turns out, most people can’t do it for long periods of time.” But “if it fits into your lifestyle, there’s nothing wrong with it,” Levitsky said.
What is the ideal diet?
Levitsky also offered a few guides for students unsure about how they should eat. First, he recommends not eating the same foods for two days in a row in order to diversify your nutrient sources constantly. Next, never eat when you’re not hungry – this is a very easy way to consume less.
Another tip he gives is to take small portions. “Perhaps the most prominent environmental signal to eat is what’s on your plate,” he said. By exercising portion control, we can simplify the dieting process substantially.
Ultimately, for those whose goal is to lose weight, they should be “eating in moderation with a variety of foods” and using the scale to objectively track progress for weight loss.