I was privileged this past week to give a talk on weight control to the work force at the US House of Representatives.
The gist of it all was- of course calories count, but who wants to spend a lifetime counting them? Yes, there is a better way. I told them about it, and am about to tell you, too.
That calories absolutely do count - despite recurring, pseudo-scholarly ruminations on the matter – ought to be irrefragable. The issue is settled independently by simple reason, basic logic, and laws of physics – to say nothing of that trifecta. The form and function, bulk and biochemistry of any organism run on energy delivered by a given fuel source. Calories quantify that energy in food.
Of course, no given number of calories reliably predicts weight outcomes for us all, any more than a given number of miles predicts running time for us all (some of us can run 2 hour marathons, most of us cannot)- but a mile is still a mile; any more than gallons of fuel predict the distance every car will travel (some cars are highly fuel efficient, some are gas guzzlers)- but a gallon is still a gallon; and so on. Calories count, but so does the nature and quality of “fuel” calories populate; so do the innumerable idiosyncrasies of the individual “machine” those calories are fueling. I’ve spent a lot of time on this topic before, more than once- it is fully baked. Time to move on.
The number of calories we require to feel full and satisfied - which, presumably, is what we are all aiming at when we start noshing – is, alas, very vulnerable to manipulation. And manipulated, it is. We have been told the tale, more than once, of scientists working for the big food companies, using functional MRI technology to determine the formulations that most reliably put our appetite centers into overdrive. Remember when they “bet” we couldn’t eat just one? The house always wins; and they are the house. Their bet was safe, and by no means limited to potato chips.
Courtesy of the ground-breaking work of Professor Carlos Monteiro and others, we can now catalogue such manipulations of our food using the NOVA classification of processing. That, in turn, has enabled expert researchers in energy balance- notably, Kevin Hall at the NIH- to isolate and assess the effects of ultraprocessing. The result is as we all might have expected, and what those who designed “addictive junk food” in the first place already knew: ultraprocessing, independent of other considerations, increases the calories we consume. And so, ineluctably, increases our weight, too- because, in case you missed the memo, calories count.
Reflecting on, and fighting against, this uneven playing field my entire career - I have been inclined to equate obesity to drowning. A human body “drowns” not because there is anything wrong with the body- but because a perfectly normal, healthy human body, working as it should, just can’t stay under water for too long. We are not fish. Similarly, a perfectly normal, healthy human body cannot cope with an unending flood of willfully hyperpalatable calories and labor-saving technology. We can drown in those, as we can drown in water. We have been doing just that for years and decades. We have potent adaptations to protect us from starving; we have adaptations that help us use our muscles as required to survive. We have zero native defenses against caloric excess and the lure of the couch…never having needed those before; never, therefore, evolving them.
What we can’t address with genetic adaptation, we can address with ingenuity – the signature attribute of our species. What willpower won’t do for us- skillpower just might.
Opposing the pernicious adulterations of the food supply that so effectively undermine our attempts at restraint is the science of satiety. Satiety refers to a lasting feeling of fullness, and the capacity of foods to confer that. The fewer the calories required to achieve satiety, the fewer we tend to consume. The greater the number, well- just ask an emptied bag of potato chips.
A number of factors influence satiety thresholds. Among the best studied is volume; foods that take up a lot of space, especially but not only those with a low ratio of calories to volume, reliably reduce the calories it takes to feel full. The most obvious illustration of this is whole fruits and vegetables- but soups and stews, which distribute calories into greater volume than drier preparations, express it, too. Macronutrients may matter, with protein inducing more satiety, calorie for calorie, than simple carbohydrate or fat. But this effect looks to be less reliable.
Fiber, which contributes to food volume, can influence satiety via other mechanisms, too- including slowed absorption of nutrients from the GI tract into the bloodstream. The effects of fiber intake on satiety appear to be quite reliable and robust.
Among the most important influences on satiety is variety. Certain flavors- notably sweet, and to only slightly lesser extents salty, and savory- stimulate appetite, and do so independently. Combine these flavors in foods and dishes, and more than one “appetite channel” is turned on at once. Have you ever met anyone who can avoid overeating at an all-you-can-eat buffet? Neither have I. The carefully ultraprocessed formulations that populate the modern food supply turn many individual foods into an analog of just such a buffet: salt hides in sweet foods (such as breakfast cereals); sugar hides in salty foods (including salty snacks); and so on. Every such food is a veritable buffet unto itself.
The tendency to fill up in a flavor-specific manner has a name: sensory specific satiety. The tendency to keep on eating when flavors are shuffled might just be called: business as usual. On the chance you aren’t fully convinced, recall some family holiday when you ate until it hurt to breathe- and still found room for dessert. Case closed.
What to do about all this?
Make your way to wholesome foods in any sensible, balanced combination. In other words: to master quantity, focus on the overall quality of your diet.
Yes, I know- there’s no pixie dust on that- sorry. It’s simple, obvious, and you might even have heard it before. None of that changes the fact that it is the one, genuine solution. Among the many virtues of wholesome foods in their native, minimally processed state is that they fill us up on fewer calories. You can control your calorie intake by focusing on quantity, and spend the rest of your life either heavier, or hungrier, than you want to be. Or you can focus on quality- fill up on fewer calories- and put both lean, and satisfied, on the same menu.
More good news on that topic: while there is just one, well established, basic theme of healthful eating for the human kind of animal, there are many, many reasonable variants on that theme. You can, and from my point of view should, find a way that lets you love the foods that loves you back. Transitioning from a diet of ultraprocessed junk generally involves a brief period of taste bud rehab- weaning your palate off a preference for such junk, and teaching it to reward you for eating actual food. It works very well, happens pretty quickly, and is a very small investment for a lifetime of returns: pleasure from both good food, and good health.
One final thing. Overall diet quality is the – yes, “the,” not “a” – leading predictor of premature death and chronic disease in the modern world. Managing calories without addressing diet quality is not just prone to fail- it misses the forest for a tree. Weight likely matters to you- but years in life and life in years certainly do, too, and the quality of your diet pertains, and powerfully, across that full expanse.
Calories count, but you’ve got better things to do than counting them for the rest of your life. Pick a way of eating you like, and maximize the quality of it. This is something each of us can manage- for ourselves, and our families, in our own house. And the house always wins.
David L. Katz, MD, MPH, FACPM, FACP, FACLM, is the Founding Director (1998) of Yale University’s Yale-Griffin Prevention Research Center, and former President of the American College of Lifestyle Medicine. He has published roughly 200 scientific articles and textbook chapters, and 15 books to date, including multiple editions of leading textbooks in both preventive medicine, and nutrition. He has made important contributions in the areas of lifestyle interventions for health promotion; nutrient profiling; behavior modification; holistic care; and evidence-based medicine. David earned his BA degree from Dartmouth College (1984); his MD from the Albert Einstein College of Medicine (1988); and his MPH from the Yale University School of Public Health (1993). He completed sequential residency training in Internal Medicine, and Preventive Medicine/Public Health. He is a two-time diplomate of the American Board of Internal Medicine, and a board-certified specialist in Preventive Medicine/Public Health. He has received two Honorary Doctorates.