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
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The last six months I have tried to eat to hit a protein target. Still strict carnivore (18-19 months) but eating pretty much more than I want each day to have enough protein for muscle growth. The proteins went up, and I didn't hit the fat targets, so I had some stiff and hard stools. I increased the fat to catch up to the proteins and help with the stools as well. In turn, so my diet has not been 'eat when hungry-eat til full' for the last six months or so.
After six to 12 months on carnivore my cholesterol dropped a few points but took a significant bounce up at the 18-month mark. I was expecting an increase with the sheer amount of food I was eating but I didn't expect the numbers to jump this much.
May thru November 2024 May 2025 November 2025
Total Cholesterol 239 212 274
LDL 185 150 164
HDL 37 39 55
Tri-G 49 43 41
My total weight loss of carnivore has been 95-96lbs and in the last couple months I gained 12-15 pounds bouncing around the 215-mark for the most part. The weight gain I expected as the lifting has become more and more a part of my day to day. I am stronger now than I can even remember (never was much on lifting) and the energy levels are still that constant/ability to keep going since early on with carnivore. I feel just as good now as I did six months ago. I had a great visit with my neurologist yesterday. (He is moving back home to Alabama so I quipped that carnivore was going to run him out of business. He replied, "I hope so".) He told me of all his NMO patients I have made the biggest turnaround and went from ho-hum numbers 18 months ago til now. All my markers are within limit is with the exception of one. I started carnivore 18 months ago, so I let people draw their own conclusions. (LOL, preaching to the choir in a forum such as this). My blood sugar crept up a little. My day-to-day over the last six months moved from the low 80's to touching the low 90's every now and then. Yesterday it was 94. Blood pressure was 100/58 before the infusion and 98/54 afterwards (laying in a recliner for five hours).
Even with the cholesterol making a jump this is how I judge my health. When I first started the infusions I was 310+lbs and was on a dumpster diet. After each infusion I would be wiped completely out. The 45-minute ride home felt like hours. I hit the recliner for a stretch then to bed really early. restless sleep all night and pretty much flat the next day. Fast forward from 18 months ago, yesterday I saw the Neurologist at 8AM, started the infusion at 9AM (use to be six hours at 310 pounds but now 5 hours at 220) and I was home by 3PM. The ride home was a simple ride home and I ate bacon, sausage and eggs mid-afternoon. I went outside and busted/split just about a Toyota truck full of red oak from two trees we had taken down last week. Fed all the animals as it got dark and back in the house. I went to bed at 9 and now I am up at my normal 3AM time frame. I checked out the forum and now off to the gym to be one of those 4AM weirdos (LOL).
I'm going to call that progress, maybe with a chunk more of fat running free in my bloodstream, but over the last 18 months, progress the same.
I don't think we make progress over months/years without stacking up a bunch of day-to-day wins.
Hope all is well with you and yours.
Scott