Researchers wanted to know if losing weight could actually slow down how fast your body ages at the cellular level. They studied 144 people with obesity who went on diets for a year and measured special “aging clocks” that track biological age. While weight loss improved many health markers like cholesterol and blood sugar control, the aging clocks didn’t change much. This suggests that even though your body gets healthier when you lose weight, the cellular aging process might work differently than scientists thought. The findings remind us that biological aging is complex and we shouldn’t rely too heavily on these aging clocks as the main way to measure health improvements.

The Quick Take

  • What they studied: Whether losing weight through dieting could slow down your body’s biological aging, measured using special tests called epigenetic clocks
  • Who participated: 144 adults with obesity who participated in a year-long weight-loss study. Half followed a low-carbohydrate diet and half followed a low-fat diet
  • Key finding: Weight loss significantly improved traditional health markers like cholesterol, insulin levels, and inflammation, but the epigenetic aging clocks showed minimal changes. This suggests these aging clocks may not be the best way to measure the benefits of weight loss
  • What it means for you: Losing weight is still very beneficial for your health based on traditional measures, but don’t expect it to dramatically change your biological age according to these new aging tests. Focus on the proven health improvements rather than chasing changes in epigenetic clocks

The Research Details

This was a controlled experiment where 144 people with obesity were divided into two groups. One group followed a low-carbohydrate diet and the other followed a low-fat diet for 12 months. Researchers measured three different types of epigenetic clocks—special tests that estimate how fast your cells are aging—at the beginning and end of the study. They also measured many traditional health markers like cholesterol, blood sugar control, and inflammation. The goal was to see if weight loss would change the epigenetic clocks and whether those changes matched improvements in traditional health markers.

Epigenetic clocks work by looking at chemical tags attached to your DNA that change as you age. Think of them like a biological speedometer that measures aging speed. The researchers used three different types of clocks (DunedinPACE, PCPhenoAge, and PCGrimAge) to get a complete picture. This approach allowed them to see if these new aging tests were sensitive enough to detect changes from weight loss.

Understanding whether epigenetic clocks respond to lifestyle changes is important because these tests are being promoted as ways to measure how well interventions work. If they don’t change with weight loss, they might not be useful for tracking the benefits of dieting. This research helps scientists understand what these aging clocks actually measure and whether they should be used to guide health decisions

This study has several strengths: it included a reasonable number of participants (144), lasted a full year (long enough to see real changes), measured multiple types of aging clocks for confirmation, and included a broad panel of health markers. However, the study was relatively small compared to some nutrition research, and all participants had obesity, so results may not apply to people of normal weight. The researchers were careful to use proper statistical methods to avoid false findings

What the Results Show

Before the diet started, one of the epigenetic clocks (DunedinPACE) was strongly connected to several health problems including high insulin levels, poor blood sugar control, high cholesterol, low good cholesterol, inflammation, and abnormal hunger hormones. This suggested the aging clock was picking up on real health issues.

After 12 months of dieting, something surprising happened: the connections between the aging clock and these health problems mostly disappeared. This means that even though people’s health improved dramatically, the aging clock didn’t change much. Only two markers—inflammation and a hormone called adiponectin—remained connected to the aging clock after weight loss.

When researchers looked at whether changes in the aging clocks matched changes in health markers, they found no significant connection. This was unexpected because scientists thought that if weight loss improved health, it should also slow down the aging clocks. The fact that it didn’t suggests these two things measure different aspects of health.

The study found that weight loss itself was very successful—people lost significant amounts of weight and their traditional health markers improved substantially. Both the low-carbohydrate and low-fat diets worked similarly well. The improvements in cholesterol, blood sugar control, and inflammation were real and meaningful, even though the epigenetic clocks didn’t change much. This shows that the aging clocks may not be capturing all the ways that weight loss benefits your health

Previous research suggested that epigenetic clocks might be sensitive measures of how lifestyle changes affect aging. This study challenges that idea by showing that while health improves with weight loss, the aging clocks don’t necessarily change. This doesn’t mean the aging clocks are useless, but it suggests they measure something different from traditional health markers. The findings align with growing scientific skepticism about whether these clocks should be used as primary targets for health interventions

The study only included people with obesity, so we don’t know if results would be the same for people of normal weight. The study lasted 12 months, which might not be long enough to see changes in epigenetic aging. The sample size of 144 is moderate—larger studies might find different patterns. The study didn’t include a control group that didn’t diet, so we can’t be completely sure that the diet caused the changes observed. Additionally, epigenetic clocks are still relatively new, and scientists are still learning what they actually measure

The Bottom Line

If you’re considering weight loss, do it for the proven health benefits like better cholesterol, improved blood sugar control, and reduced inflammation. Don’t rely on epigenetic aging clocks as your main measure of success. Instead, focus on traditional health markers that your doctor can measure and that have clear connections to disease prevention. (Confidence: High for traditional markers; Low for epigenetic clocks as intervention targets)

People with obesity considering weight loss should care about this research because it clarifies what actually improves with dieting. Healthcare providers should be cautious about promoting epigenetic clocks as primary measures of health improvement. People interested in anti-aging should understand that these new aging tests may not respond to weight loss the way we hoped. This research is less relevant for people at normal weight or those not planning to diet

Traditional health improvements from weight loss typically appear within 3-6 months. However, epigenetic aging changes (if they occur) may take much longer—possibly years—to become measurable. Don’t expect to see changes in epigenetic clocks within a year of dieting

Want to Apply This Research?

  • Track traditional health markers that actually changed in this study: weight, cholesterol levels, fasting blood sugar, and inflammation markers (if available through your doctor). These show real, measurable improvements from weight loss
  • Use the app to monitor weight loss progress and traditional health markers rather than focusing on biological age estimates. Set goals based on losing 5-10% of body weight and improving cholesterol or blood sugar levels, which have proven health benefits
  • Check weight weekly, get blood work done every 3-6 months to track cholesterol and blood sugar, and monitor how you feel (energy levels, fitness improvements). Skip expensive epigenetic aging tests as a way to measure diet success—they don’t appear to change with short-term weight loss

This research suggests that epigenetic aging clocks may not be reliable measures of short-term health improvements from weight loss. While weight loss has proven benefits for traditional health markers, you should not use epigenetic aging tests as your primary way to measure diet success. Always consult with your healthcare provider before starting a weight-loss program or making significant dietary changes. This study does not replace medical advice, and individual results may vary. If you have obesity or related health conditions, work with your doctor to develop a personalized weight-loss plan based on proven health markers rather than epigenetic clocks.