Scientists Reveal Why Bread Can Cause Weight Gain Without Overeating17 April 2026 ByDavid Nield (Photographer Basak Gurbuz Derman/Moment/Getty Images) New research in mice shows how eating bread can cause body weight and fat mass to increase, even though caloric intake stays at a similar level. The research, led by a team from Osaka Metropolitan University in Japan, highlights how carbohydrates can contribute to weight gain as well as excessive fat intake – which is what dietary advice tends to focus on. This isn't the first time nutritionists have talked about bread and carbohydrates and their contribution to weight gain, but there hasn't been much detailed research into the relationship – especially wheat flour – or into what might be happening at a metabolic level. The team discovered that eating more wheat bread was associated with reduced energy expenditure, pushing the metabolism towards a state where fat storage is prioritized, even when the calories in a diet stay at a similar level. The researchers analyzed the difference that bread in the diets of mice had on their weight (A) and fat tissue (B, C). (Matsumura et al., Mol. Nutr. Food Res., 2026) "These findings suggest that weight gain may not be due to wheat-specific effects, but rather to a strong preference for carbohydrates and the associated metabolic changes," says nutritionist Shigenobu Matsumura of Osaka Metropolitan University. The researchers set up experiments in which lab mice were given a choice between their normal, healthy cereal-based diet and either simple bread, baked wheat flour, or baked rice flour. The mice were then monitored to check their weight and how their bodies burned calories at rest and when active. Using blood samples, the study team also examined hormone, blood sugar, and metabolite levels in the animals, while post-experiment tissue analyses assessed gene expression in the liver. The experiments showed that the mice strongly preferred to switch from their standard diet to carbohydrate-heavy snacks, which then led to weight gain and more fat tissue in the mice, particularly in the males. Further analysis and follow-up tests suggested that these two key changes were being driven not by overeating or a lack of exercise, but by the foods themselves. In the wheat flour diet, fewer calories were being burned overall, while genes responsible for turning carbohydrates into fat were activated. Another follow-up test focusing on the wheat flour group showed that when the chow diet was restored, the weight gain stopped, and the metabolic shifts were reversed. "In the future, we hope this will serve as a scientific foundation for achieving a balance between 'taste' and 'health' in the fields of nutritional guidance, food education, and food development," says Matsumura. The findings are more evidence of how what we eat can cause changes in how our body processes food and burns the calories it contains. In the case of bread, it seems to slow down the body's metabolic engine. One limitation of the study is that it used mouse models, rather than human volunteers. While it's likely that similar processes are happening in people, it's not certain – so that's something future studies can pick up. The researchers also want to experiment with a broader selection of foods to identify what exactly it is about bread that causes this reaction. No diet study like this exists in isolation, of course. We know that a variety of other factors can also impact how our metabolism reacts to food and drink, including age and hormone-related changes. Related: There's a Surprising Link Between a Key Nutrient, Obesity, And Alzheimer's Risk Further research should help establish the role that wheat and bread can play in a diet and how the simple "calories in, calories out" rule isn't always straightforward. "Going forward, we plan to shift our research focus to humans to verify the extent to which the metabolic changes identified in this study apply to actual dietary habits," says Matsumura. "We also intend to investigate how factors such as whole grains, unrefined grains, and foods rich in dietary fiber, as well as their combinations with proteins and fats, food processing methods, and timing of consumption, affect metabolic responses to carbohydrate intake." The research has been published in Molecular Nutrition & Food Research. ARTICLE SOURCE: https://www.sciencealert.com/scientists-reveal-why-bread-can-cause-weight-gain-without-overeating
The most-used herbicide on Earth just flunked a major safety test
Glyphosate, the active ingredient in Roundup, has been sprayed on food crops for decades. It’s used not only to kill weeds—but also to dry out wheat, oats, lentils, and chickpeas right before harvest, a practice called desiccation, which is illegal outside of the US.
This makes our breads and grains uniquely toxic, turning glyphosate into a debate almost as hot as seed oils.
New safety data this month has shocked the world, causing the EU to reevaluate it's already strict guidelines. Let's explore.
Even EU levels are unsafe
In June 2025, scientists from the Ramazzini Institute published the Global Glyphosate Study in Environmental Health. It was a two-year rat trial designed to mimic real-world exposure—specifically at the EU’s “safe” level of 0.5 mg/kg body weight per day.
What they found:
• Significant increases in leukemia and non-Hodgkin's lymphoma
• Tumors in the thyroid and liver
• Effects appeared even at the lowest dose tested—which mirrors the EU legal limit
How does the U.S. compare to the EU on glyphosate?
1. "Safe" Daily Limit:
• EU: 0.5 mg/kg body weight (EFSA)
• U.S.: 1.75 mg/kg body weight (EPA)
2. Food Testing:
• EU: Only ~1.7% of foods tested show glyphosate (EFSA Pesticide Residue Report)
• U.S.: No federal testing; independent labs show widespread contamination
3. Cereal Contamination:
• EU: Mostly non-detectable or under 100 ppb
• U.S.: Up to 2,837 ppb in Quaker Oatmeal Squares (EWG, 2018); up to 500 ppb in 2023 retest (EWG, 2023)
4. Bread Products:
• EU: Glyphosate rarely detected
• U.S.: Up to 1,150 ppb in whole wheat bread (Detox Project, 2020)
ppb = parts per billion. These levels are technically legal—but they raise serious questions in light of the Ramazzini findings.
Why oats and wheat get hit the hardest
It’s not just about what’s grown. It’s how it’s harvested.
In cooler or wetter regions, farmers spray glyphosate 3–5 days before harvest to dry the crop evenly. This isn’t for weeds—it’s for convenience. And it leaves the chemical sitting right on the grain.
High-risk foods:
• Conventional oats
• Wheat bread and crackers
• Lentils, chickpeas, and hummus
• Granola bars and "healthy" cereals
This practice, called pre-harvest desiccation, is banned or restricted in several countries. In the U.S., it’s business as usual.
Can you lower your glyphosate levels?
Yes. Fast.
The Organic for All Study tracked four families across four U.S. cities who switched to an all-organic diet.
After just six days, their urinary glyphosate levels dropped by 70 percent.
This wasn’t a detox protocol. It was just a grocery list.
What you can do right now
The best thing you can do is just eat meat. As a carnivore glyphosates are not an issue but for those who prefer more of a keto styled diet it’s best if you follow these guidelines.
• Buy organic—especially for oats, wheat, lentils, and chickpeas.
• Look for “glyphosate-free” certified products.
• Swap in safer carbs. Rice, corn, potatoes, and sweet potatoes are never desiccated.
• Support regenerative farms that avoid chemical harvest sprays. Look for “no spray” claims on-pack.
• Question “healthy” snacks. If it’s made with conventional oats or wheat, assume glyphosate unless proven otherwise.