Following the eruption of the “If it fits your macros” movement, many have been led to believe that food selection is irrelevant to body composition or health outcomes, assuming ingested calories, macronutrients, fibre and sodium are fixed.
Thus, we have a divide within the fitness community. On one end of the spectrum, we have those promoting paleo, plant-based and vegan diets with an emphasis on unprocessed foods. On the other end of the spectrum we have the devout “flexible dieters” promoting the incorporation of energy-dense, micronutrient-poor, highly palatable sweets and junk foods within their calorie and macronutrient allowance.
So, what’s the low down? Will a Pop-Tart laden diet deliver the same results as one energetically matched with fruits, vegetables and wholegrains? Sure, putting up photos of your Snickers Bar that you’re eating in a diet phase will look cool for Instagram, but are you doing yourself and the community a disservice? Let’s try to explore this question by looking at a brand-new study directed by Kevin Hall and colleagues. Worthy of noting, a causal relationship between processed food consumption and human obesity has yet to be established, nor has any trial demonstrated beneficial effects of reducing processed foods in the diet.
The study in question investigated 20 adults following either a processed or an unprocessed diet for 14 days, matched for calories, sugar, fat, sodium, fibre and macronutrients. All participants trialled both the processed and unprocessed diet arms, in random order.
During each diet arm, the participants were provided with three daily means and told to eat as much or as little as desired. While the nutrient composition of the three meals in both diet arms were matched as described above, they differed substantially in the calories derived from processed or unprocessed foods.
Upon analysis, when participants were exposed to the processed meals, they ate approximately 500 calories more each day compared to the unprocessed meals. During the provision of the processed meals, participants also consumed 280 calories more worth of carbohydrate, and 230 calories more worth of dietary fat, with a slight reduction in the amount of protein that was consumed. Interestingly, despite the overconsumption of processed food calories, participants did not report differences in the pleasantness of the diet arms, suggesting the differences in energy intake were not due to greater palatability.
Additionally, hunger, fullness and meal satisfaction were not different between the diet arms, which is surprising given the significant extra calories consumed in the processed arm. Meal eating rate was also significantly faster during the processed diet by approximately 10 calories per minute and may partially explain the overconsumption of calories without differences in hunger ratings. An alternative explanation could be derived from the observed increase in the appetite-regulating hormone PYY, and decrease in ghrelin levels during the unprocessed diet, which theoretically provides a state of greater satiety and less hunger.
Here’s where the above changes start to really become evident and demonstrate the notable impact of processed food options on the attainment of your physique related goals. During the unprocessed diet arm, participants lost roughly 1kg of body weight. However, during the processed diet arm participants actually gained 1kg. Body fat was also decreased by 0.3kg during the unprocessed diet but increased by 0.4kg during the processed diet.
So, what are the Chinese Takeaways from this piece? What ammo do we have for taking on the zealot-like IIFYM’ers bragging about the 3 slices of pepperoni pizza they could fit into their daily calories after fasting for 18 hours?
- Eliminating or reducing processed foods from the diet decreases calorie intake and results in better weight loss
- A diet high in processed foods increases calorie intake and encourages weight and fat gain
- Processed foods may lead to weight gain by causing a faster eating rate
- A diet high in unprocessed foods may support appetite management by increasing levels of PYY (satiety hormone) and decreasing levels of ghrelin (hunger hormone)
- Processed diets may be deleterious by encouraging the overconsumption of carbohydrate and fat, but not protein
- A processed diet higher in calories is no more satiating than an unprocessed diet with lower calories