How Food Processing Affects Your Weight and Health
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What are ultra-processed foods?
Ultra-processed foods (UPFs) are foods made in factories using ingredients you wouldn’t normally use at home. They often contain additives, colorings, and preservatives. Common examples include packaged snacks, sugary cereals, soft drinks, frozen ready meals, and some plant-based meat substitutes. These foods are designed to be convenient and tasty, but they’re often less healthy than whole or minimally processed foods.
What did this new study look at?
A group of researchers in the UK wanted to find out how UPFs affect weight and health — even when the overall diet follows healthy guidelines. They ran a controlled study with 55 adults who were overweight or obese and regularly ate a lot of UPFs. Each person followed two different 8-week diets, one after the other:
- One diet was made up of minimally processed foods (MPF) like fresh fruits, vegetables, plain rice, meat, fish, and legumes.
- The other was mostly ultra-processed foods (UPF) like packaged breads, cereals, and ready meals — but still followed national nutrition guidelines.
All meals were delivered to participants' homes, and they were allowed to eat as much as they wanted. This setup helped the researchers see how food processing itself — not just nutrients — influenced health.
What did the study find?
Both diets led to some weight loss, but the minimally processed food diet helped people lose more weight. On average:
- People lost 2.06% of their body weight on the MPF diet
- People lost 1.05% of their body weight on the UPF diet
That might not sound like much, but over a year, it could lead to a 9–13% weight loss with MPF compared to just 4–5% with UPF.
The MPF diet also led to better results in fat loss, body fat percentage, and appetite control.
Why did the MPF diet perform better?
Even though both diets followed healthy nutrition guidelines, there were key differences:
- Lower energy intake: People naturally ate about 500 fewer calories per day on the MPF diet, likely because of lower energy density and slower eating speed.
- Better appetite control: People on the MPF diet reported fewer cravings and better control over emotional or impulsive eating.
- Less gastrointestinal discomfort: Although mild issues were common in both diets, more people on the UPF diet reported problems like constipation, reflux, and fatigue.
What about cholesterol and blood sugar?
Surprisingly, both diets showed some improvement in cholesterol and blood sugar markers. The MPF diet lowered triglycerides more, while the UPF diet slightly reduced LDL cholesterol.
This shows that healthy UPFs — like fortified cereals or low-sugar ready meals — aren’t completely bad, but they still don’t offer all the benefits of less processed food.
What does this mean for your diet?
The main takeaway is simple:
If you want to lose weight and improve your health, focus on eating fewer ultra-processed foods — even if your diet already seems “healthy” on paper.
Try these practical tips:
- Cook at home more often using fresh ingredients
- Read labels and avoid foods with long ingredient lists
- Swap packaged snacks for whole fruits, nuts, or yogurt
- Limit ready meals and fast food, even those marked as “healthy”
- Plan your meals so you don’t rely on convenience foods
Final thoughts
This study shows that not all “healthy” diets are equal. How your food is made matters just as much as what’s in it. By cutting back on UPFs and choosing more natural, minimally processed options, you can make a real difference in your weight, cravings, and overall health.