A recent study published in Clinical Nutrition found that wholegrain rye did not outperform refined wheat for weight loss over a 12-week period, but it did lead to reduced inflammation and beneficial changes in gut microbiota among adults with overweight or obesity, according to findings released on Mar. 24.
The research is significant because it addresses ongoing questions about the potential health benefits of wholegrain rye compared to refined wheat, especially for individuals at risk of metabolic diseases. Obesity and related conditions are major public health concerns worldwide, prompting continued investigation into effective dietary interventions.
In the RyeWeight2 randomized controlled trial conducted by researchers in Denmark and Sweden, 255 adults with body mass indexes between 27 and 35 were assigned either a calorie-restricted diet based on wholegrain rye or one using refined wheat. Both groups lost weight—3.2 kg (7 lbs) for the rye group and 2.9 kg (6.4 lbs) for the wheat group—but these differences were not statistically significant.
However, participants consuming wholegrain rye experienced a notable reduction in C-reactive protein levels—a marker of systemic inflammation—and higher levels of plasma butyrate, an anti-inflammatory short-chain fatty acid. Metagenomic analysis showed increased levels of Bifidobacterium adolescentis in the rye group, while some bacterial species linked to negative health outcomes decreased compared to those eating wheat.
Unexpectedly, people with higher baseline insulin resistance had poorer weight loss outcomes when eating wheat rather than rye. This suggests that individuals with greater initial insulin resistance or inflammation might benefit more from a wholegrain-based diet.
Although this study did not replicate earlier findings suggesting superior weight loss effects from rye consumption, researchers said differences may be due to variations in participant age and baseline insulin sensitivity between studies. The authors concluded that while short-term weight loss was similar between diets, "rye has anti-inflammatory effects and can alter the gut microbiome in ways that may have positive implications for cardiometabolic health." They suggest future research should explore how individual biology could inform personalized dietary recommendations.
