For years we have been told that obesity is the result of eating too much and exercising too little. This principle is known as energy balance. Energy is consumed in the form of calories in the foods we eat. Energy can be burned off by physical exercise. There are even charts that show us how certain amounts of specific exercises can burn off a certain number of calories. We have been told that for every 3500 calories consumed more than what we burn off, we gain a pound. 3500 calories is particularly convenient because if we can burn off 500 calories a day more than we consume, we can lose a pound over the course of a week. The bad news, however, is that if we consume 500 calories a day more than we burn off, we can gain a pound a week, 52 pounds a year and 520 pounds between now and 2027.
Now we are hearing that it is not about the calories after all. This perspective suggests that we get fat from consuming fast food and processed food. The worst thing about these foods is that they contain too many carbohydrates, particularly refined carbohydrates, such as white bread and sugar. We are proceeding down a progression from all calories are created equal to some calories are more equal than other calories to calories don’t really count after all. Recommendations include going vegan to adopting a plant-based diet to eating as much saturated fat as you want as long as it doesn’t come from fast or processed food.
Let’s say that I go out and splurge on a chocolate milkshake. Before consuming it, I weigh the treat and find out that it weighs exactly one pound after subtracting the weight of the cup. I also learn that the shake contains 610 calories (based on a shake weighing 454 g). I carefully weigh myself right before I consume this decadent beverage and right after I suck up the last remaining vestige of the brown liquid rolling around in the bottom of the cup. The scales tell me that I gained an entire pound as I rapidly consumed that chocolate delight, but that is not how it will ultimately affect my weight.
A more reasonable but less satisfying choice
A nutritionist will tell me that the shake I consumed contains water and some other non-digestible material that in time will come out the other end. He will indicate that if I am concerned about my weight, my main concern is those 610 calories. If those calories from the milkshake are not replacing what I normally eat that day it will likely cause me to increase my weight slightly. Using the formula above I calculate that I would gain 3500/610=0.174 pounds or 2.79 ounces. The nutritionist would explain that since I am older and am not as active as I used to be I should not rely on that formula too much. If anything I would probably gain more weight. If, however, I used the shake to replace a meal in part or completely, it might not contribute to any weight gain. Actually, the body tends to compensate, through various signals, by decreasing appetite when I consume too much and increasing it when I consume too little over a course of a few days. The good thing about the milkshake is that it does contain milk and contributes some vitamins and minerals. The bad thing is that I am consuming massive amounts of sugar that are not contributing to good health.
A friend of mine who advocates for a plant-based diet tells me that I should not listen to the nutritionist as his advice is really nutritionism, an outdated way of looking at foods and health. She says that my milkshake not only has way too much sugar, it also has way too much animal fat. It is not really the calories that are the problem it is the animal fat and refined sugar that will make me fat. I am told that I really need to minimize as much animal fat as I can. If I must have a shake I need to make my own and use either raw honey or maple syrup to sweeten it, but I would be better off with a fruit smoothie or almond milk if I insist on a shake. I can never have that moment in time and all the damage it did with that fructose coursing in my arteries and finding its way to my liver will turn it directly into fat!
So should I believe the nutritionist or the advocate of a plant-based diet? As a scientist, I side with classic nutrition research. Nutritionists and dietitians operate on the basis of a consensus of data-based studies that have been conducted over a long period of time. They believe in the importance of being aware of the calories we consume and their relationship to energy balance. Nutrition scientists are willing to revise their viewpoint based on a series of studies that suggest current recommendations are misguided or in error, but they are not ready to be blown about in the winds of dramatic news stories around the results of a single study that suggest that everything we know about a nutritional issue is wrong.
Advocates of a point of view that is contrary to established science, however, evaluate the results of a single dramatic story in terms of how it supports their point of view. If the story goes contrary to that point of view, the results are rejected out of hand. If it supports their point of view, it serves as final proof that they were right all along and everyone else is a victim of false information. I came across a story not too long ago that suggested that we tend to view any dramatic story as the final act of a play. Science does not work like that, each study tends to be a single piece of a giant jigsaw puzzle with more pieces to come. I take the jigsaw-puzzle perspective.
Faithful readers of my blog have probably guessed that my consumption of a sugar-laden milkshake was not a true story. I watch very carefully how much sugar I consume because I am a borderline diabetic. I do believe that the bottom line as far as obesity is concerned is the balance between calories consumed and calories burned. In the first chapter of In Defense of Processed Food1, I describe other factors that can affect our chances of becoming obese as does Sylvia Tara in The Secret Life of Fat2. Although we present different perspectives, we both emphasize the importance of calories. All of us must be careful not to fall for the latest discovery or latest diet fad. I agree most Americans eat too much meat, but meat is an excellent source of vitamins and minerals. By avoiding meat and all other animal products, it becomes harder to obtain essential vitamins and minerals, particularly if we place additional restrictions on plant ingredients such as avoiding all or some grains. I agree that most Americans consume too much sugar, but the idea that we can substitute honey and maple syrup for table sugar and high-fructose corn syrup is folly. These natural sugars are just as filled with fructose as the refined ones. To get the benefit all the extra minerals in honey and maple syrup, we need to consume way too much fructose.
We want definitive yes/no answers which the science of nutrition is unable to provide. General guidelines found at websites such as the one run by the Academy of Nutrition and Dietetics provide usable information that makes sense. Chasing after the latest healthy food rabbit is not likely to satisfy in the long run and could even prove dangerous. Extreme diets tend to be more likely to create new health problems than solve current ones.
1 Shewfelt. R.L., 2017. In Defense of Processed Food, Cham, Switzerland: Copernicus
2 Tara, S., 2017. The Secret Life of Fat, New York: W.W. Norton & Company