Last summer Mark Haub, PhD, an associate professor of nutrition at Kansas State University, lost 27 pounds over 8 weeks on a diet that sourced two-thirds of his food from junk-food snack cakes—specifically Ho Hos®, Little Debbie® cakes and Twinkies®.

“Perfect!” you sigh, exasperated, thinking of the diet balance mantra you give to clients who are struggling with junk-food snacking and who have plateaued in their weight loss efforts. When a story like this makes headlines and clients come in waving the newspaper clipping at you or include links to the story in e-mails to you full of questions, what can you say?

Experiments like Haub’s and those of others—which set out to prove that a calorie is a calorie no matter what its source—can undo the careful education you deliver to clients about eating whole foods and about protein, good fat and nonprocessed carb balance in the diet.

For starters, you can tell clients that more calories expended minus fewer calories taken in really works. That part is elementary. Haub cut back from 2,600 to 1,800 calories per day, which is absolutely the right energy balance approach for weight loss. But are all calories created equal? Do 200 calories’ worth of potato chips or snack cake have the same thermodynamic effect on the human body as 200 calorie’s worth of fruit or hummus and whole-wheat pita bread? A study published last year in Food & Nutrition Research suggests that there is a big difference.

Sadie B. Barr and Jonathan C. Wright of the department of biology at Pomona College in Claremont, California, studied whether a particular processed-food (PF) meal had a greater thermodynamic efficiency than a comparable whole-food (WF) meal, thereby conferring a greater net-energy intake. According to their abstract, “Empirical evidence has shown that rising obesity rates closely parallel the increased consumption of PF in the USA. Differences in [postmeal] thermogenic responses to a WF meal vs. a PF meal may be a key factor in explaining obesity trends.”

The researchers measured subjective satiation scores and postmeal energy expenditure for 5–6 hours after meals of equal energy value were ingested. The meals were either “whole” or “processed” cheese sandwiches: multigrain bread and cheddar cheese were deemed whole, while white bread and processed cheese product were considered processed. Meals were comparable in terms of protein (15%–20%), carbohydrate (40%–50%) and fat (33%–39%) composition. Subjects were 17 healthy men and women, studied in a crossover design.

Results showed there were no significant differences in satiety ratings after the two meals. However, average postmeal energy expenditure for the WF meal (17 ± 14.1 kilocalories [kcal], 19.9% of meal energy) was significantly higher than for the PF meal (73 ± 10.2 kcal, 10.7% of meal energy). This led Barr and Wright to conclude that average postmeal energy expenditure was nearly 50% lower after the PF meal in this study than after the WF meal of the same caloric value. “This reduction in daily energy expenditure has potential implications for diets comprised heavily of PFs and their associations with obesity,” they said.“… a lot of our leaders have come to office on the bank accounts of the big food industry, big ag and big oil—that’s how our system works. It’s a system that’s broken and it speaks to the incredible importance of each and every individual to lend their talents to creating the solution that we want to see.”