A lifestyle study of more than 1,100 adults at University Hospital Tübingen in Germany, published in Nature Medicine in 2025, found that around 22 percent of participants who lost no weight during a one-year lifestyle program still returned their blood sugar to a normal range.
Over as much as nine years of follow-up, those who normalized their glucose without shedding pounds were up to 71 percent less likely to develop type 2 diabetes than those whose blood sugar stayed in the prediabetes range - a reduction almost identical to the 73 percent seen in participants who did lose weight.
The finding does not mean readers can skip the effort. The people who reversed their prediabetes still changed how they ate and moved, they just did not see the change reflected on the scale.
The insight from the Prediabetes Lifestyle Intervention Study is that the number worth tracking is fasting blood sugar, not body weight. Prediabetes describes a blood sugar level that is higher than normal but not yet in the diabetes range.
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Around 115 million American adults, more than 2 in 5, currently meet that definition, according to the Centers for Disease Control and Prevention. Roughly 8 in 10 do not know they have it.
Where the weight moved, not how much
The Tübingen team compared people who normalized their blood sugar without weight loss to those whose blood sugar stayed in the prediabetes range. The responders had shifted fat away from the abdomen.
Body weight looked similar between the two groups, but visceral fat, the fat wrapped around internal organs, was lower in responders, and more fat sat under the skin. Insulin sensitivity and beta-cell function both improved.
The body's own GLP-1 response also worked better. That is the hormone system copied by semaglutide, the active ingredient in Novo Nordisk's Ozempic and Wegovy.
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That distinction matters because visceral fat is more closely linked to insulin resistance than total body weight is. Endurance training and diets rich in unsaturated fats are among the levers that can shift where the body stores fat, the researchers wrote in The Conversation.
What the Tübingen researchers say the numbers mean
Prof. Andreas Birkenfeld, who led the work, framed the result as a reset for how patients and doctors set goals.
"Restoring a normal fasting blood sugar level is the most important goal in preventing type 2 diabetes and not necessarily the number on the scale," he said in the Helmholtz Munich announcement about the study.
His colleague Prof. Reiner Jumpertz-von Schwartzenberg argued the shift should reach clinical guidelines.
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"In future, guidelines for the prevention and treatment of type 2 diabetes should not only take weight into account, but above all blood glucose control and fat distribution patterns," he said.
The Tübingen team also reported that the pattern held up when they checked it against data from the U.S. Diabetes Prevention Program, the reference lifestyle trial for prediabetes in the United States.
What it means in practice
The takeaway is not that exercise and diet stopped mattering. It is that the scale can miss the win.
Someone who walks daily and swaps refined carbohydrates for vegetables, fish and olive oil may see their weight barely move and still cut their diabetes risk substantially, provided their fasting blood sugar improves.
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Anyone in the prediabetes range should talk with their doctor about fasting glucose, A1C and waist measurements before setting personal goals. The Tübingen results are observational at the subgroup level, meaning they show a strong association, not a personal guarantee. But the direction is consistent across the German cohort and the U.S. replication data.
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