Since I left off with BMI, let’s pick it back up with our waist measurements. Just in the past year, new studies have shown that our waist measurements, or more precisely, our waist measurements divided by our hip measurements, may be a better indicator of our risk of premature death. Some people might have a normal BMI but carry all their fat around their “middle,” which seems to increase the risk for heart disease (and therefore premature death). At the same time, some others, especially high-intensity athletes, might have a BMI greater than 25 but have almost no body fat anywhere: their higher weight is all in muscle and bone. But for the time being and probably a long time to come, BMI is here to stay as an index of whether you’re overweight, because it’s still a lot easier to step on a scale than to find that tape measure you carefully put away somewhere.
So, some folks attribute overweight or the ability to stay at a normal weight mostly to the tendencies we inherited from our parents and some attribute it to the abundance of delicious food in our environment and the challenge of making “good” food choices. But think about it: whether you blame your mother’s thighs (and genes) or the donut shop at the corner for keeping you fat, if you don’t do the work to learn to take control, you’re giving up. I’ll devote lots of future blogs to maintaining a healthy weight or losing weight and keeping it off, but for now, let’s talk about how the foods we eat deliver the nutrients we need.
The amounts of protein, carbs, essential fats, vitamins, and minerals healthy people should consume on average were discovered by feeding people in laboratories. With slight oversimplification, the amounts of each nutrient that were needed to allow certain bodily functions to proceed normally and to prevent the effects of deficiencies were the basis for the dietary requirements. Separate requirements have been set for age groups from 2 years to 70 years, for men and women, and for women who are pregnant or breastfeeding. The confusing numbers you see on the Food Facts labels are based on the needs of an average adult consuming 2000 calories per day (the more calories we need to maintain our weight, the more of many nutrients we need.)
What do our bodies need each of those nutrients for? Table 1 shows some of the functions each nutrient carries out in our bodies. But as much as this table should convince us to consume a varied balanced diet, it has 2 problems. First, if your goal is building muscles, you might think you can just focus on eating foods that contained only protein and ignore everything else – but if you were somehow able to do that, it would be a disaster: Your body wouldn’t be able to do anything with the protein in the food because you would be lacking in the fat, vitamins, and minerals, not to mention energy your body needs to process and deliver the protein to your muscles! Second, tables like this one sometimes give the false impression that the protein we eat is directly applied to our muscles, the fat immediately absorbed into our…thighs! SO WRONG!
First, everything we eat, EVERYTHING, is a combination of nutrients. You don’t eat individual nutrients: that steak protein comes along with a lot of possibly unwanted saturated fat, as well as a little unsaturated fat, water, and much needed iron, zinc, and a number of other minerals and vitamins. Bread and pasta contain complex carbs but also proteins and various B vitamins, and in the case of bread, an unexpected amount of sodium (salt).
Sugar-sweetened soda is essentially nothing but sugar and water: no vitamins or minerals, the quintessential empty-calorie food. Juice drinks are sugar-sweetened water with some fruit flavoring and a little bit of vitamins thrown in but for the amount of calories they pack (in sugar), they’re hardly an ideal source of those vitamins. Actual fruit juice (without added sugar) does have most of the nutrients found in actual fruit, but it’s not an ideal food: often vitamins like C are destroyed during processing or storage, needed fiber may be removed, and the juice is nowhere near as filling as whole fruit. Fruits are best consumed fresh, frozen, or canned in water alone (not sugar syrup) for the fiber, vitamins, minerals, and other antioxidants they provide. Any food that contains some fruit, whether it’s a smoothie, candy, or some filled pastry may give you a little bit of the nutrients in fruit, but isn’t nearly as complete as the actual fruit and usually packs a lot of additional calories.
The same can be said for vegetables…raw or roasted veggies: great! Veggie colored/flavored pasta spirals are no better than any white flour pasta (not terrible, just not a vegetable substitute).
Second, the foods we eat are digested into their component nutrients. The sugar and flour (starch) in a cupcake or a slice of whole wheat bread starts being broken down in your mouth, and this process continues in your stomach and intestines; the resulting tiny glucose molecules travel throughout your whole body (especially your brain) to deliver energy to every cell. If you eat more carbohydrates (or protein or fat) than you need in a given day, they’re ALL converted to the fat we see on our thighs or waistlines… The protein from the milk, eggs, and butter in the cupcake is broken down into tiny components called amino acids (a lesson for later); the liver then sops them up and delivers them to where they are needed—to rebuild muscle, and make new enzymes. The fat in the chocolate and butter is also partially broken down, formed into new molecules called triglycerides and then delivered by the cholesterol in the bloodstream to the cells that need it.
For the vast majority of people, the body’s need for all the different nutrients varies little from one day to the next (exceptions being women who are pregnant or nursing, very high-intensity athletes when they are training or playing, and people who are very ill). As much as we like to believe we’re all unique, science has not yet found strong enough evidence to prove that some people just need more of one vitamin or another or that some people should eat less or more protein. Companies that promise to test your blood type, hair, DNA, or gut microbes, and provide you with a customized diet are just stealing your money right now! Unless you have a diagnosed condition such as phenylketonuria, diabetes, celiac disease, or a true food allergy, the scientific evidence shows that your health is best protected and your intake of needed nutrients is most ensured by eating a variety of real foods, a balanced diet.
How do you know if you’re eating a balanced diet? You may read or hear that a balanced diet should consist more or less of 50% carbohydrates, 20% protein, and 30% fat, but as I have said, we choose foods, not nutrients, and 99.9% of foods comprise a multitude of nutrients. The “balanced” diet can much more easily be visualized by imagining a dinner plate divided into 4 equal slices: one slice should be foods like meat, chicken, fish, dairy foods, legumes, nuts, and certain grains (foods that tend to be higher in protein and fat); one slice should be foods like bread, rice, and pasta, preferably 100% whole grain (a topic for a later blog); and starchy vegetables (potatoes, winter squash, corn, all foods that that tend to be higher in complex carbohydrates – starch and fiber), and the remaining two slices of the plate (half the plate) should be filled with a variety of vegetables and fruits in as close to their original state as possible. In fact the government thought that this divided plate is such a useful way to apportion the foods you need to eat that it has replaced the old food pyramid you might have heard about. Just remember that next to the plate needs to be a drinking glass full of water, although no one is exactly sure how big or how much.
What about things like chips, pastries, sugar-sweetened soda, booze, ice cream, and candy? Do they have a place on the plate? Nutrition scientists agree that most of the foods we eat should be contributing needed nutrients. Calorie-dense foods like chips, pastries, and candies are fine but not if they’re crowding out nutrients we need or adding extra calories to a full-day’s supply. That’s why if you tend to be on the small, thin end of the spectrum, unless you work out regularly, you just don’t have much room on that plate for the little extras.
In the United States, not many people suffer from deficiencies in most nutrients these days, at least not the kind that cause diseases like scurvy or Beriberi. Instead, the role that nutrition plays, especially over-nutrition (eating too much) in whether we get chronic diseases—heart disease, heart attacks, strokes, cancer, diabetes—has been a topic of great interest, extensive research, and controversy for the past 40 to 50 years. It is this research that has led to public health messages to eat less fat, and more recently to eat less saturated fat, specifically. You might also have heard the message to eat a more plant-based or Mediterranean diet. Eating less of animal foods (especially higher-fat red meat and whole milk dairy products), highly processed foods, and high-fat snacks and desserts, and more vegetables, vegetable sources of fat (nuts, olive oil, and avocado), legumes, and whole-grain breads and pastas has shown some evidence—in studies that follow large groups of people over a long time—of helping delay chronic diseases. Finally, you may be getting the message to cut down on salt and foods that are high in sodium because of its apparent link to heart disease. These issues will be topics of future blogs!