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
Wanted to make a dedicated thread about ketone testing and ketosis. As I learn, more and more of this makes sense.
I finally bought a blood ketone meter, and have been testing my ketone levels each morning now.
I have to say that I was really surprised by the results, and further surprised that I was NOT achieving functional ketosis nearly as quickly as I had hoped. My levels have been languishing in the .8 realm without additional fasting! For the record, I eat a really clean diet, but the foods that keep me from reaching good keto numbers were things that should never contain any form of sugar or carbohydrate, yet I saw a small rise in blood sugar, as well as corresponding lower keto numbers at the next morning's test. We bought smoked brisket the other night from one of the local restaurants in the area. Who wouldve thought that BRISKET would have added sugars?! Anyway, the meter has added a lot of clarity to the picture for me, and although the stinking test strips are about a dollar each, at this point in the game, its WORTH IT to me to know!
This will surely be a lot of review for many here, but I will post what I have learned anyway: When we begin to strive for ketosis, we often have leftover glucose stored as glycogen in the liver. This stored glycogen must be depleted FIRST before ketones are produced and we begin entering ketosis. This is glycogenolysis. Stored glycogen is typically exhausted within the first day or so of either fasting, or a proper diet as we strive for here. Fasting does bring about functional ketosis much sooner.
I also now know that our bodies produce three types of ketones! Acetoacetate ketones will only account for roughly 20 percent of the ketones our body is producing, and are the variety that can be detected by the cost effective urine test strips. Beta Hydroxybutyrate will make up the remaining bulk of the ketones being produced, with a slim number given to acetone, being the third type. Beta Hydroxybutyrate can only be sampled via the blood test strips, as in the meter I have.
I purchased the KETOBM meter, for better or worse. All meters I researched have a small number of negative reviews that do claim inaccuracy. While this was disheartening, I have also ordered the urine test strips (which havent arrived yet) to remove any uncertainty about test results. Ideally, the strips and the meter will agree,
Let me know your thoughts!