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
Like most, prior to carnivore I ate a dumpster diet. And within that dumpster diet I could eat five-gallon buckets at the time. And then do it again and again.
After starting carnivore and gradually ending up on one meal per day (OMAD) I have found I can't eat at that volume anymore. I'm totally impressed with the amounts I hear others can eat. In the past I could eat a big steak, half my wife's steak with a loaded potato, several glasses of sweet tea and then dessert. Follow that with a snack before I went to bed. Now it is just about all I can do to eat the large steak. And with that one steak I am good for at least 24 hours. No hunger whatsoever.
Recently in an attempt to hit a protein target I started with protein powder and then an occasional pre-mixed protein drink. The pre-mixed drink got 50 grams within the day, but it had 11 grams of sugar and carbs (but I forget how many). Soon after putting two and two together I found within an hour of drinking the protein/sugar infused drink I was actually hungry. I tried to offset it with drinking water to proof it was hunger and indeed, it was hunger. So, I ate. I repeated it a few days/week later and it was the same. In the past three to four weeks the only thing that has changed is the addition of 11 grams of sugar maybe twice per week. My appetite has increased drastically to the point I have gained 12 pounds this month.
The intent was to get improvements in the gym and the last month or so I have seen a lot of progress, both in the mirror and counting plates.
Since carnivore is more of an elimination diet than it is a fats/protein diet I am starting to wonder about the 'meat is satiating' references.
Before carnivore I could eat twice as much meat with all the other stuff and since eliminating sugar one big steak is my limit. As I have re-introduced some sugar/carbs my appetite has drastically increased.
Which one is carrying the biggest stick? Is it the satiating meat or the triggers from sugars/carbs. My "individual/just me" experiment indicates sugar/carbs are more powerful to in the body, and maybe the mind than fats and proteins.
Scott