Rules of thumb for maintaining healthy lifestyles may seem ubiquitous. They dictate how many steps we should be getting in a day or how many glasses of water we need to stay hydrated. But how many of these goals have been backed by science, and how many should be put back on the shelf?
Here are five common health goals that you may have heard of and the scientific research that either validates them, or discredits them.
1. Use the Food Pyramid for Balanced Meals
The typical pyramid, with grains at the bottom, fats at the top, and fruits, vegetables, and dairy in between, may have been our first introduction to balanced meals. But this method of meal planning is actually outdated, with origins tracing back to World War II, when food sources were scarce, and rationing was necessary, according to Britannica.
When it comes to improved nutritional guidelines, according to Paige Cunningham, assistant professor of nutritional sciences at Cornell University, MyPlate is now the way to go.
“It’s beneficial for obesity prevention, potentially, and we know this from epidemiological data and randomized control trials,” she says. “It’s striking a balance between all of the different food groups so that we can make sure we are getting that dietary variety that can offer all the nutrients we need for a healthy lifestyle.”
Specifically, MyPlate visualizes a plate half-filled with fruits and vegetables, with the other half quartered into proteins and grains. It also suggests consuming healthy unsaturated fats in moderation.
It isn’t the gospel of dieting, as experts in the Journal of the Academy of Nutrition and Dietetics in 2014 emphasized; it’s more so a method to inspire healthier and more conscious eating practices.
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2. Drink Eight Glasses of Water a Day
Another classic health goal is to drink at least eight cups of water per day. Drinking adequate amounts of water can lower our risk of developing kidney stones and help remove waste from our bodies, according to a study in Springer Nature Link. But such a myth can be misleading.
“The challenge with that recommendation is that first of all, there’s no evidence that that amount of water is needed,” Cunningham says. “Humans are very good at physiological regulation of hydration status. We drink when we’re thirsty, and that thirst occurs before dehydration. So we’re very good at maintaining the hydration balance that we need.”
Moreover, water isn’t our only source of hydration. According to Cunningham, lots of water-rich fruits and vegetables can help with hydration.
According to Tufts University, women should aim to drink 11 cups, while men should aim for 15 cups of water each day. But ultimately, how much you really need depends on factors like how much you’re moving in a day and the climate where you live.
3. Walk 10,000 Steps Each Day
The idea that 10,000 steps per day is the golden amount for a healthy lifestyle is another popular health myth.
“Very few people get that number of steps, and getting that number of steps doesn’t seem to be necessary,” Cunningham says. “A lot of studies are finding that anywhere between 6,000 to 8,000 steps can confer benefits to health.”
Indeed, a 2019 study published in JAMA Internal Medicine examining the relationship between step counts and mortality rates in older women found that mortality rates progressively decreased with increasing step counts, peaking at around 7,500 steps per day. How intense those steps were didn’t have as much impact on mortality rates as long as they happened in the first place.
Likewise, another recent article published in Lancet Public Health by an international group of researchers reviewing the field found that striving for 7,000 steps a day led to improved health outcomes, ranging from mortality rates to even depressive symptoms.
“There does seem to be a sort of dose-response effect, whereby the more steps you get, the better, but it plateaus at those higher numbers,” Cunningham says.
As for where the number 10,000 came from, a Harvard researcher who co-authored the JAMA study traced its origins to a 1965 marketing campaign by a Japanese company to sell pedometers.
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4. Cutting Calories Is More Important For Weight Loss Than Exercise
When it comes to getting your daily steps or other forms of exercise and movement, you might’ve heard that diet plays a much larger role in weight loss than you think. This idea does hold some credence, as researchers have found that exercise alone does not trim weight by much.
“If you think about the energy that we consume from food, it’s a lot easier to cut out calories from diet than it is to cut out those calories from physical activity,” Cunningham says.
That doesn’t mean that dieting alone is the key to weight loss: A 2020 study in Women’s Health found that combining healthy eating and exercise habits tended to lead to the most beneficial outcomes, with improvements in both physical and mental health.
Exercising is also helpful for maintaining weight, Cunningham adds, as keeping a consistent weight even after losing it can be quite challenging for several reasons.
Though seeing consistent, obvious results from dieting and exercise can be challenging, experts writing in a study in Diabetes Spectrum argue that people should stick with it — if only because of the numerous other health benefits of an active lifestyle, ranging from improved mental health to reduced risk of heart disease and diabetes.
5. BMI Is an Ideal Measurement for Health
Body mass index (BMI) has long been used as a health indicator, though it doesn’t offer a direct diagnosis of obesity or the amount of body fat, according to a study in JAMA Network Open. The measurement has come under fire in recent years, with scientists debating whether its continued usage is necessary.
BMI has origins dating back to 1835, initially developed as a way to compare the weights of different people at different heights, though it has evolved over time. Researchers have cautioned that it isn’t easily generalizable to all populations, especially those that have been historically underrepresented, according to a study in Springer Nature Link.
For example, people may have higher BMIs despite lower body fat due to greater muscle mass. The health index cannot account for all cases and body types.
“For individuals that fall out of that normal range for muscle mass, it’s perhaps not the best metric,” she says. “But for the average person, it’s highly correlated with disease risk, and it’s a pretty easy and approachable way to assess body fat percentage and adiposity.”
Experts have similarly argued that the limitations of BMI could be addressed by considering other health measures, such as waist circumference or bone mass.
“I think all of these different measures have their place, and I think that we maybe can start using a combination of different metrics, but I wouldn’t by any means say that BMI is useless,” Cunningham says.
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What Is The Best Rule Of Thumb For Health?
There is ultimately no single golden rule for a perfectly healthy life — our bodies are a conglomeration of our circumstances, habits, and movements, and putting a number to anything we do or are, with certainty, is difficult. However, for some, Cunningham says, following rules of thumb with solid scientific backing can help set achievable goals.
As with all things in nutrition, balance and nuances are necessary, according to Cunningham, alongside a healthy dose of skepticism. Something that works for one person might not for the next.
“Everyone needs to follow what works for them,” she says.
This article is not offering medical advice and should be used for informational purposes only.
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