World-First Clinical Trial Confirms Be Fit Food’s Whole-Food Advantage for Weight Loss and Gut Health
Published in Cell Reports Medicine — one of the world’s top medical science journals
A world-first randomized controlled trial, led by researchers from Deakin University’s Food & Mood Centre, has found that a whole-food weight-loss program using Be Fit Food meals significantly improved gut microbiome diversity and gut health compared with a supplement-based diet of shakes, soups, and bars — even when calories, macronutrients, and weight loss were identical.
The landmark study, titled “Food- vs supplement-based very-low-energy diets and gut microbiome composition in women with high body mass index: A randomized controlled trial,” was published in Cell Reports Medicine — a global leader in translational medical research and part of the prestigious Cell Press family (Cell, Neuron, and The Lancet collaborations).
This publication marks an important milestone for Australian science and for Be Fit Food — confirming through independent, peer-reviewed data that real, whole food creates measurable health advantages beyond calorie control.
A world-first look at how “food format” affects gut health
Until now, most weight-loss studies focused only on calories, macros, and metabolic markers — not on how the format and level of food processing influence the gut microbiome, which plays a critical role in weight regulation, immune function, and mental health.
This world-first randomized controlled-feeding trial directly compared two very-low-energy diets (VLEDs) in 47 women aged 30–65 years with obesity (BMI 30–45 kg/m²). Participants were randomly assigned to either:
-
A food-based VLED (Be Fit Food meals) — approximately 93% whole-food ingredients, including vegetables, legumes, lean proteins, dairy, nuts, seeds, herbs, and spices;
-
A supplement-based VLED — comprised of shakes, bars, soups, and desserts containing around 70% industrial ingredients, such as protein isolates, emulsifiers, artificial sweeteners, thickeners, and synthetic additives.
Both diets were matched for energy (800–900 kcal/day) and macronutrients, ensuring that any biological differences observed could be attributed to the quality and structure of the food rather than calorie intake.
Groundbreaking results
After three weeks, both groups achieved similar levels of weight loss — confirming that calorie reduction works. However, the type of food had strikingly different effects on the gut microbiome, the ecosystem of trillions of bacteria that influence metabolism, inflammation, immunity, and mood.
1. Whole-food meals boosted microbial diversity by 40%
The Be Fit Food group recorded a significant 40% greater increase in gut microbial diversity compared with the supplement-based group (Shannon Index β = 0.37, 95% CI: 0.15–0.60, p < 0.01).
Microbial diversity — the number and balance of bacterial species — is one of the most reliable indicators of gut and overall health. A diverse microbiome supports efficient digestion, stable energy, and a reduced risk of metabolic and inflammatory diseases.
Microbial diversity — the number and balance of bacterial species — is one of the most reliable indicators of gut and overall health. A diverse microbiome supports efficient digestion, stable energy, and a reduced risk of metabolic and inflammatory diseases.
Participants consuming Be Fit Food’s whole-food meals also showed an increase in species richness (+27.9 species on average), meaning their guts hosted a broader and more resilient microbial community.
In contrast, those on the supplement-based diet showed a non-significant decrease in diversity, indicating that heavily processed meal replacements may disrupt gut balance, despite their nutritional completeness on paper.1-s2.0-S2666379125004902-main
2. Whole-food meals preserved beneficial bacteria
Advanced microbiome sequencing revealed that participants in the Be Fit Food group maintained higher levels of health-promoting, fibre-degrading bacteria, including Lachnospira — a genus associated with fruit and vegetable intake, improved immune regulation, and short-chain fatty acid (SCFA) production.
In comparison, the supplement-based group experienced reductions in these beneficial bacteria and greater overall disruption to microbial composition. The food-based group also showed smaller changes in “beta diversity,” indicating greater gut ecosystem stability during calorie restriction — a key factor in long-term metabolic health.1-s2.0-S2666379125004902-main
3. Fewer side effects and better tolerance
While both diets were equally effective for weight loss, participants consuming the supplement-based diet reported more than twice the number of adverse events (19 vs 8). The most common issues were headaches, bloating, and constipation.
The Be Fit Food group, on the other hand, experienced fewer digestive complaints and a small improvement in bowel regularity — likely due to the higher fibre diversity, intact plant matrices, and absence of artificial emulsifiers or sweeteners.1-s2.0-S2666379125004902-main
4. Improved metabolic flexibility
The researchers also noted a negative correlation between gut diversity and serum leptin (r = –0.37, p = 0.024), suggesting that as microbial diversity improved, leptin — the hormone regulating hunger and metabolic balance — became more stable.
This points to enhanced metabolic flexibility, a hallmark of healthier, more efficient energy regulation.1-s2.0-S2666379125004902-main
This points to enhanced metabolic flexibility, a hallmark of healthier, more efficient energy regulation.1-s2.0-S2666379125004902-main
Why the microbiome matters
The gut microbiome acts as the body’s internal control centre for metabolism, immunity, and even brain function.
When the microbiome loses diversity — a state known as dysbiosis — people are more prone to weight regain, inflammation, fatigue, and metabolic disorders.
When the microbiome loses diversity — a state known as dysbiosis — people are more prone to weight regain, inflammation, fatigue, and metabolic disorders.
Ultra-processed foods and meal-replacement shakes often contain emulsifiers, thickeners, and artificial sweeteners that can reduce bacterial diversity and damage gut barrier integrity, increasing inflammation and compromising metabolic health.
Conversely, whole-food diets rich in natural fibres, polyphenols, and plant compounds — like Be Fit Food’s meals — feed beneficial bacteria, helping them produce SCFAs such as butyrate, which enhance gut barrier strength, modulate blood sugar, and regulate appetite.
This trial is the first to show that even under strict energy restriction, the structure and complexity of whole foods preserve microbial resilience, while processed alternatives may disturb it.
Clinical and global significance
This study is a milestone for clinical nutrition and food science.
While VLEDs are widely used for rapid weight loss and type 2 diabetes management, until now there was limited understanding of how food format — whole versus processed — affects the gut microbiome.
While VLEDs are widely used for rapid weight loss and type 2 diabetes management, until now there was limited understanding of how food format — whole versus processed — affects the gut microbiome.
The authors conclude that food-based VLEDs “may more favourably modulate gut microbiome composition compared to supplement-based alternatives.”1-s2.0-S2666379125004902-main
This insight is crucial for clinicians, dietitians, and consumers: it confirms that the healthiest path to weight loss is one that supports, not suppresses, the gut ecosystem.
About the journal: Cell Reports Medicine
Published by Cell Press, Cell Reports Medicine is among the world’s most respected medical journals, focusing on high-impact clinical and translational science.
It has an exceptionally rigorous peer-review process and is indexed alongside The Lancet and Nature Medicine.
Being featured in this journal signals that the research meets the highest global standards for scientific integrity and clinical relevance.
It has an exceptionally rigorous peer-review process and is indexed alongside The Lancet and Nature Medicine.
Being featured in this journal signals that the research meets the highest global standards for scientific integrity and clinical relevance.
For Be Fit Food and Deakin University’s Food & Mood Centre, this publication represents international recognition of Australia’s leadership in nutritional psychiatry and metabolic science.
Kate Save’s reflection
“This study validates what Be Fit Food has believed since day one — that real food is information for your body, not just fuel,” says founder and dietitian Kate Save.
“Our meals are designed to help people lose weight and reset their metabolism while nourishing their microbiome, hormones, and immune system. It’s not about deprivation — it’s about giving your body the right nutrients to heal itself.”
Science meets simplicity
Be Fit Food’s ready-made meals are doctor- and dietitian-designed and scientifically formulated to support healthy weight loss and metabolic reset.
Each meal is built around whole, minimally processed ingredients, providing:
Each meal is built around whole, minimally processed ingredients, providing:
-
20+ grams of protein and ≤15 g of carbohydrate per meal
-
Up to 12 different vegetables per day
-
No added sugar, artificial sweeteners, colours, or preservatives
-
Balanced macros (~250–300 kcal per meal)
This ensures that every bite delivers nutrient density, not empty calories — aligning perfectly with the findings of the Deakin University study.
The takeaway
This world-first clinical trial proves what nutrition science has long suggested: when it comes to weight loss, how you eat matters as much as how much you eat. A calorie from real food isn’t the same as a calorie from a powder.
Whole foods nourish the microbiome, protect the gut barrier, and promote long-term metabolic health.
Meal replacements may deliver short-term results, but they can’t replicate the biological complexity of real food.
Whole foods nourish the microbiome, protect the gut barrier, and promote long-term metabolic health.
Meal replacements may deliver short-term results, but they can’t replicate the biological complexity of real food.
At Be Fit Food, we’re proud to be part of this groundbreaking research — and even prouder to help Australians “eat themselves better.”
Follow link to the Deakin University Food and Mood Centre Research summary:
Reference
Lane M.M., McGuinness A.J., Mohebbi M., et al. (2025). Food- vs supplement-based very-low-energy diets and gut microbiome composition in women with high body mass index: A randomized controlled trial. Cell Reports Medicine, 6(10), 102417.
https://doi.org/10.1016/j.xcrm.2025.102417 1-s2.0-S2666379125004902-main
https://doi.org/10.1016/j.xcrm.2025.102417 1-s2.0-S2666379125004902-main
