Many people judge the success of a diet by one simple number on a scale. If weight is lost, the diet is considered successful. If the weight eventually returns, many people believe all the effort was wasted.
A new study suggests that this view may be overly simplistic. Researchers have discovered that the body may retain important health benefits from earlier lifestyle changes, even after weight regain occurs.
The research, published in the journal Circulation, was led by scientists from Ben-Gurion University of the Negev and a team of international collaborators. Their findings point to a specific type of fat called visceral fat as a key driver of long-term health outcomes.
Visceral fat is sometimes referred to as hidden belly fat. Unlike the fat that can be pinched under the skin, visceral fat lies deep inside the abdomen and surrounds internal organs. Because of its location, it behaves differently from other fat deposits. It produces hormones, inflammatory substances, and chemical signals that can affect the entire body.
Scientists have long suspected that visceral fat contributes to conditions such as type 2 diabetes, heart disease, high cholesterol, and insulin resistance. However, less was known about what happens years after visceral fat is lost.
To answer this question, researchers followed participants from two major dietary intervention trials known as CENTRAL and DIRECT-PLUS. These studies tested different approaches to healthy eating, including Mediterranean diets, low-fat diets, low-carbohydrate diets, and a plant-rich green Mediterranean diet combined with exercise.
The original interventions lasted 18 months, but the researchers continued monitoring participants for five and ten years afterward through a project called FIT, short for Follow Interventions Trials.
A total of 366 participants completed long-term follow-up assessments. Using advanced 3.0-Tesla MRI scanners, researchers measured several types of fat throughout the body. This technology allowed them to distinguish between visceral fat, deep abdominal fat, superficial abdominal fat, liver fat, and pancreatic fat with exceptional precision.
The results challenged many traditional assumptions about weight loss. By the time of long-term follow-up, participants had regained most of the weight they originally lost. On average, body weight had returned to baseline.
If researchers had looked only at the scale, they might have concluded that the benefits of the intervention had disappeared. However, MRI scans told a different story.
The investigators found that abdominal fat stores remained lower than they had been before the interventions began. Most importantly, reductions in visceral fat were partially maintained even years later. This finding suggests that the body may preserve some of the protective effects of earlier lifestyle improvements.
The researchers then examined how these changes related to future health. Visceral fat stood out from every other type of fat measured.
Each 10 percent reduction in visceral fat achieved during the original intervention was associated with a 30 percent lower risk of developing type 2 diabetes during long-term follow-up. The relationship was dose-dependent, meaning greater visceral fat loss was linked to greater protection.
A five percent reduction corresponded to a 17 percent lower diabetes risk. A fifteen percent reduction was associated with a 40 percent reduction in risk. Participants who reduced visceral fat by twenty percent experienced approximately a 50 percent lower risk of future diabetes.
These benefits were observed even after accounting for body weight changes, physical activity levels, dietary adherence, and other health measures. In contrast, fat stored in the liver, pancreas, and under the skin did not consistently predict future diabetes risk.
The findings support the idea that visceral fat may be one of the most important targets for disease prevention. Professor Iris Shai described the phenomenon as a form of metabolic memory. According to this concept, the body retains biological benefits from previous reductions in harmful visceral fat even after some weight returns.
The study also found that visceral fat loss was linked to lasting improvements in insulin resistance, overall cardiometabolic risk, and metabolic syndrome severity. These are important markers because they influence the likelihood of developing chronic diseases later in life.
The research has several strengths that make the findings especially convincing. The ten-year follow-up period is unusually long, participant retention was exceptionally high, and MRI imaging provided accurate measurements that are rarely available in large studies.
Nevertheless, the study has limitations. Because it is observational during follow-up, it cannot conclusively prove cause and effect. Participants may have differed in other ways that influenced their health outcomes. Additional studies will be needed to confirm the findings in different populations.
Even so, the results have important practical implications. They suggest that people should not become discouraged if they regain some weight after a successful period of healthy living.
The benefits of earlier lifestyle improvements may not disappear entirely. Reducing visceral fat appears to leave behind a lasting protective effect that may continue supporting metabolic health for years.
Review and analysis: The study represents a significant advance in understanding long-term weight loss outcomes. Rather than focusing solely on body weight, it highlights the importance of fat distribution, particularly visceral fat.
The findings suggest that successful interventions should be evaluated by their impact on internal fat stores as well as weight. If future research confirms these results, doctors may increasingly use imaging and waist measurements rather than BMI alone when assessing long-term health risk.
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Source: Ben-Gurion University of the Negev.
