What has puzzled me for years is how little some people claim to eat, yet 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. While the caloric content of a food is determined by measuring how much energy is released by burning a set amount of that food in a lab setting, results likely vary within a biological setting.
Over decades of pondering this conundrum, there’s been an explosion of obesity cases coinciding with the exponential development of ultra-processed foods (UPFs). Coincidence? I think not. Perhaps, the caloric energy of these highly processed foods is more easily accessible to the body than that from whole foods. To understand my reasoning, let me describe different levels of processing.
Food processing has come a long way from the old-time preservation methods of salting, drying, and fermentation. Eggs and fresh whole produce are considered unprocessed. Minimally processed foods include meat and fish (gutted, butchered, and sold fresh, frozen, or canned), dairy (pasteurized, fermented), and produce (peeled, cut, and perhaps salted before being frozen, chilled, canned, or fermented).
Some foods need processing to become culinary ingredients like oils, flour, and sugar. Oils can be pressed from seeds, nuts, and fruits although some are derived using chemical extraction. 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 unprocessed, minimally processed or culinary ingredient categories.
Over time, new processing techniques were designed to avoid wasting food and for convenience (like Velveeta® and Spam®). But 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 creation of UPFs has accelerated 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, fats, and other 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, culinary ingredients can be softened by overcooking, treated with acid or enzymes, or so finely milled that flavors explode as the food crunches or melts in your mouth. These tempting flavor profiles encourage overeating.
Here’s the downside: They are essentially pre-chewed or pre-digested, which improves caloric availability. Since the UPF ingredients are reduced to fine particles, just about every single calorie will be absorbed. Think about it—little work is required by one’s gut to break them into smaller molecules for absorption as compared to bulkier whole or minimally processed foods. Moreover, they also dissolve 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 sooner than with UPFs. So, despite your body’s best efforts, whole foods are often incompletely broken down and their calories are not fully absorbed.
But those leftover bits are not wasted. The unabsorbed, poorly fragmented food pieces and fiber are transported to your large intestine where colonic bacteria degrade these scraps for their own energy needs which also supports a healthy gut microbiome. Conversely, UPFs leave little for beneficial bacteria to feed on, potentially leading to gastrointestinal issues like constipation and “leaky gut.”
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 not by the body. 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 as compared to that of a UPF dish.
UPFs affect blood sugar control, too, since finely ground carbohydrates are efficiently absorbed. For instance, many 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 either short-term storage or for processing into the building blocks for fat. So…sugars not used by the muscles will be stored mostly as fat which explains why sedentary people gain weight so easily. 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? In general, you must read labels. Ugh. Look past the few initial recognizable ingredients on snacks and convenience foods to find 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 contains no 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.
To summarize, food choices impact weight and sugar control. Instead of counting calories, one might instead eat way fewer UPFs and more whole foods. Although convenience and snack foods are appealing, cooking “from scratch” is better if you have the time and resources. Following this plan may allow you to turn the trajectory of your weight gain around.
Here are some recommendations to cut back on UPFs:
**Be aware of UPF products. Read ingredient and nutritional labels. Some products 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 offerings.
**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 (high or very low shelf) 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, OK, but a separate trip is inconvenient, so maybe laziness will change your mind.
**Dilute 100% juices 1:1 with water or seltzer.
**Learn to bake from scratch. Play with the recipe—decrease sugar, substitute a bit of whole grain flour for white, add some ground flax seeds, and maybe 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.
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