All Food Calories Are Not Created Equal

What has puzzled me over the years is how little some people claim to eat, but they still gain weight.  After all, the conventional wisdom is that if one consumes 3500 calories more than they “burn,” one will gain one pound and if someone eats 3500 calories fewer than their metabolic needs and activities demand, they will lose one pound.  Yet, calories are measured by how much energy is released by burning a set amount of food in a lab setting, not in a biological setting.

Over decades of pondering this conundrum, I’ve noticed the explosion of obesity cases has coincided with the proliferation of ultra-processed foods (UPFs).  I can’t help but think that the caloric energy of highly processed foods is perhaps more easily accessible to the body than that from whole foods.  But first, we must understand the different levels of processing. 

Food processing has come a long way from its preservation methods of salting, drying, and fermentation.  Other than perhaps being washed, eggs, fruits, and vegetables are totally unprocessed.  Minimally processed foods include meat and fish (gutted, butchered, and sold fresh, frozen, or canned) as well as produce (peeled, cut, and perhaps salted before being frozen, chilled, canned, or fermented).  Oils are pressed from seeds, nuts, and fruits.  Grains can be dehulled for use as whole product, or polished, cracked, partially milled, or milled more finely to produce flour for baking.  Most foods made “from scratch” use ingredients from these categories.  

Over time, more processing techniques were designed to avoid wasting food and for convenience (like Velveeta® and Spam®).  What has changed significantly over the past 50 to 60 years is the growth of food science and the hugely successful industrial processing of ingredients to invent new foods, especially snacks.  “Ultra-processed foods” really came into their own in the 1970s (although this moniker was not coined until 2009) and the development of UPFs has exploded over the past 3 to 4 decades.

So, what exactly are ultra-processed foods?  UPFs are fabricated by food scientists in labs where they break down basic ingredients (like milk into whey and casein) and combine the resulting components with salt, sweeteners, and lab-made flavor enhancers, coloring agents, emulsifiers, thickening agents, stabilizers, artificial flavors, and preservatives to design highly palatable products.  They might even add vitamins and minerals to bestow some virtue.  

With ultra-processing, ingredients are softened by overcooking, treated with acid or enzymes, or so finely milled so that the flavors explode as the food crunches or melts in your mouth.  Not only are fiber and micronutrients removed, but the biggest downside is also that just about every single calorie will be absorbed since the UPF’s ingredients are already reduced to fine particles.  Little work is required by one’s stomach and intestines to break them into smaller molecules for absorption as compared to bulkier whole or minimally processed foods.  They are essentially “pre-digested,” which improves calorie availability.

UPFs have tempting flavor profiles and are easily chewed which may lead a person to eat more.  They also smush down to nothing in your stomach, so a full sensation is not easily achieved.

On the other hand, whole foods like meat and fish, fruits, vegetables, beans, and whole grain, seeded bread require a lot more chewing.  Your mouth, stomach, and intestines work harder to digest whole foods.  Indeed, you are expending some energy to get the caloric value from this food.  Moreover, the food spends more time in your stomach, thus contributing to a full sensation.

Despite your body’s best efforts, whole foods are often incompletely broken down.  The unabsorbed, poorly fragmented food bits and fiber are transported to your large intestine where colonic bacteria degrade these leftovers for their own energy needs which also supports a healthy gut microbiome.  Conversely, UPFs leave little for beneficial bacteria to feed on.

In short, a dish using whole foods and fresh produce may be equivalent in calories as the same ultra-processed dish by lab standards, but the “exercise” of chewing, increased effort to digest chunky foods, and the incomplete absorption of a higher fiber meal means there will be a reduced net caloric value for a meal of minimally processed ingredients.

UPFs affect blood sugar control, too, since finely ground carbohydrates are so efficiently dealt with.  For instance, ultra-processed foods contain sugars and simple starches which are quickly broken into simpler sugars.  Unless they are eaten with protein-containing foods to slow the stomach’s action (like cookies with milk, white bread with peanut butter, crackers with cheese), they move through rapidly.  The resulting sugars are absorbed as soon as they land in the small intestine, entering the blood stream in a burst, and stimulating a quick (and sometimes large) insulin release from the pancreas. 

Insulin supports sugar uptake by muscles and its delivery to the liver for short-term storage or for processing into the building blocks for fat.  For people with a sedentary lifestyle, sugars not used by the muscles will be stored mostly as fat.  Whole foods, on the other hand, take longer to break down as they move along the digestive tract, slowing the absorption of their nutrients, and leading to a less radical release of insulin.

So how does one recognize a UPF to avoid it?  The labels of most snacks and convenience foods contain a few recognizable ingredients typically followed by additives with derivative-sounding ingredients (like high fructose corn syrup or modified food starch) or chemical-like names.  While most UPFs are marketed to the general population, some are created for niche markets: sports-related, gluten-free, plant-based, and even organic although the latter does not contain the lab-made chemical additives.

In short, one person’s daily allotment of 2500 calories of ready-to-eat meals, snack foods, and sugary beverages is not the equivalent of 2500 calories of minimally processed foods. 

It seems obvious that food choices impact weight and sugar control, yet most people don’t want to count calories.  Although convenience and snack foods are appealing, a simple (but not easy) fix is to eat way fewer UPFs and substitute more whole foods.  Following this plan may allow you to turn the trajectory of your weight gain around. 

I realize that for some this is a matter of choice, but for others, convenience foods provide sustenance when there are limited funds, no refrigeration or place to cook, or multiple work and life commitments with no time.  These are inequities that need to be addressed to contain the obesity epidemic.  At least school-provided meals made with real food would be a good start.

Here are some recommendations to cut back on UPFs:

**Be more aware of UPF products.  Keep reading about them and read ingredient and nutritional labels.  Some are worse than others.

**Learn to cook.  Simple cooking is often the healthiest. 

**Change buying habits—don’t buy UPFs from warehouse clubs (huge amounts!) and avoid convenience stores and gas station stores.

**Change food shopping habits—shop the perimeter for produce, dairy, meats and seafood and avoid most of the center aisles except for staples like oil, tomato sauce, pasta, rice, beans, and frozen produce. 

**Change eating habits–don’t eat while watching the tv, scrolling, or reading. 

**Change food storage habits—put UPF foods out of sight and healthy foods where they can be seen.

**Avoid buying the truly unhealthy products (soda pop, juice drinks, candy bars, melt-in-your-mouth products, junk food, and many baked treats and frozen specialties).  If you must have them, make a separate trip so it’s inconvenient.

**Dilute 100% juices 1:1 with water or seltzer.

**Learn to bake from scratch and have these treats available for special events.  Decrease sugar, substitute a bit of whole grain flour for white, add some ground flax seeds, and unless there are allergies, add nuts to the recipe to improve its health quotient. 

**Instead of a fast or a “cleanse,” eat nothing but unsalted and low sugar whole foods for a couple of days to reset your taste buds.