In 2019, an excellent study was performed to demonstrate the differences in weight change when comparing a diet of equal calories but using unprocessed vs processed foods as variables.
The findings reinforce a message we want to get across here at Embody Nourish and that is a whole-foods diet is significantly better for your health and wellbeing when compared to the standard highly processed diet that many of us consume today.
The Unprocessed vs Processed Diet Study
The study was an inpatient randomized controlled trial involving 20 weight-stable individuals. People were randomized to have either a diet of ultra-processed or unprocessed diets for a period of 2 weeks then given the alternate diet for a further 2 weeks. The ultra-processed and unprocessed meals were matched as closely as possible in calories, energy density, macro-nutrients, sugar, salt and fibre. People in the study were allowed to eat ad libitum (without any restrictions).
The researchers found that the processed foods group gained from 1.3 lbs / 0.6kgs up to 2.6 lbs / 1.2kgs in weight in only two weeks. Study participants consuming unprocessed foods for 2 weeks actually lost from 1.3 lbs / 0.6kgs up to 2.6 lbs / 1.2kgs in weight
They also found that when eating ad libitum, the processed foods group consumed significantly more calories per day. And we’re not talking only 100 calories or so. It was anywhere between 402 to 614 calories per day in excess. That’s equivalent to 1-2 main meals for many people!
They also found that the processed foods group would consume more carbohydrates and fats per day than the unprocessed food group as well.
If we have a look at what was actually actually consumed in the study for the processed vs unprocessed groups, one could argue that the processed foods group was actually eating healthier than what a lot of Western society consumes on a daily basis:
Important to note is that the unprocessed meals in this study actually contained processed oils, milk, cheese and meats. So it was not entirely whole-foods and unprocessed. We can imagine though that if these very calorie dense foods were eliminated, the results would be even more positive for the unprocessed foods group.
Essentially, the unprocessed food participants of the study ended up being 2.6 to 5.2 lbs / 1.2 to 2.4 kgs lighter in weight than the processed food participants in just 2 weeks. This is despite both groups eating freely without restrictions and the foods being matched for calories and energy densities. While this study only lasted a short period, based on its findings we can assume the difference eating unprocessed vs processed foods could make over a lifetime.
The results of the study shows just how important calorie density is on the foods we consume. Processing foods remove a lot of its fibre contents which then makes it more calorie dense for the same volume of its unprocessed counterpart. Basically this means that for the same amount of calories , there will be quantitively more unprocessed foods compared to processed foods.
When we learn this it becomes obvious why the unprocessed study group was able to freely satisfy their hunger, eat more food and yet still consume less calories and lose significant weight compared to the processed foods group.
How This Applies To Us
Based on the findings of the study, we should strive to increase the amount of unprocessed whole-foods and drastically reduce or eliminate processed foods in our diets. We can do this instantly overnight or in a step-by-step manner – whatever suits our needs.
As opposed to currently recommended restrictive patterns, eating whole-foods ad libitum can also improve our relationship with food by allowing us to reach satiety for each meal. Due to lower calorie densities, it essentially allows us to eat more food without excessive calorie intake and can actually lead to weight loss if desired.
Hall KD, Ayuketah A, Brychta R, et al. Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake. Cell Metab. 2019. https://www.ncbi.nlm.nih.gov/pubmed/31105044