Minimally Processed Diet Leads to Greater Fat Loss todayheadline

Can two diets with identical nutrients lead to different health outcomes? A new randomized crossover trial led by researchers at University College London suggests they can.

Even when meals followed the same national dietary guidelines, participants eating minimally processed foods lost nearly twice as much weight as those consuming ultra-processed alternatives. The study, published August 4 in Nature Medicine, provides fresh evidence that food processing—not just nutrient content—plays a pivotal role in weight and body fat regulation.

Study Design: Testing UPF vs. MPF Under Equal Guidelines

The trial enrolled 55 adults in England with overweight or obesity and high habitual intake of ultra-processed food (UPF). Each participant was randomly assigned to two 8-week diets, both adhering to the UK’s Eatwell Guide but differing in food processing:

• Minimally processed food (MPF): meals made from whole ingredients like oats, vegetables, and fresh meat
• Ultra-processed food (UPF): ready meals, packaged snacks, and reformulated products like oat bars and frozen lasagna

Participants ate ad libitum—meaning as much or as little as they wanted—and received all meals at home. A 4-week washout period separated the two diet phases.

Key Findings: Weight, Fat Mass, and Craving Control

Both diets resulted in weight loss, but the MPF diet had a clear edge:

• MPF diet: −2.06% weight change
• UPF diet: −1.05% weight change
• Difference: −1.01% (P = 0.024)

The greater weight loss on the MPF diet came from reductions in fat mass and total body water, with no loss in muscle mass. Participants also reported:

• Significantly greater reductions in food cravings on the MPF diet
• Improved control over cravings, especially for savory foods
• A daily calorie deficit nearly 170 kcal greater on the MPF diet

“The effect was nearly double on the minimally processed diet,” said Dr. Samuel Dicken, first author of the study. “Though a 2% reduction may not seem very big, that is only over eight weeks and without people trying to actively reduce their intake.”

Why Processing Still Matters—Even With Healthy Nutrients

Notably, both diets were nutritionally matched for fat, sugar, fiber, protein, and salt. This challenges the assumption that nutrient balance alone is enough for effective weight management.

Professor Chris van Tulleken emphasized that “not all ultra-processed foods are inherently unhealthy based on their nutritional profile.” But even when UPFs were reformulated to meet health guidelines, they were still more energy-dense, more palatable, and likely consumed more rapidly than MPF meals.

Participants rated the MPF meals as less flavorful and convenient than UPF meals, which may have contributed to lower consumption. The UPF diet was also linked with higher reports of gastrointestinal discomfort, fatigue, and minor infections.

Cardiometabolic Markers: Mixed Signals

Both diets led to modest improvements in blood pressure, cholesterol, and glucose markers, but few differences were statistically significant between them. Triglycerides fell more on the MPF diet, while LDL cholesterol dropped more on the UPF diet. Researchers caution that longer-term studies are needed to assess these differences.

Policy Implications: Processing as a Public Health Target

Less than 1% of the UK population follows the Eatwell Guide fully, and most people consume over half their calories from UPFs. The study suggests that even when following dietary guidelines, replacing UPF with MPF offers additional benefits—particularly for fat loss and craving regulation.

“This study highlights the importance of ultra-processing in driving health outcomes in addition to the role of nutrients,” said van Tulleken. “It underlines the need to shift the policy focus away from individual responsibility and on to the environmental drivers of obesity.”

The authors call for clearer food labeling, taxes on unhealthy products, and public subsidies to make minimally processed foods more affordable and accessible.

Looking Forward: Real Food for Real Health

Participants in the study were not told to restrict calories, yet those eating real, minimally processed foods naturally consumed fewer calories and lost more fat. If these patterns continued for a year, researchers estimate that men could lose 13% of their body weight and women 9% on the MPF diet—versus only 4–5% on the UPF diet.

In a food landscape dominated by convenience and packaging, the study offers a simple but powerful message: how we make our food matters as much as what’s in it.

Journal: Nature Medicine
DOI: 10.1038/s41591-025-03842-0

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