Scientists studied 145 Japanese adults who followed a low-carb diet and exercise program for 8-12 weeks to see if their genes predicted weight loss success. While genes do influence obesity risk, the study found that genes alone couldn’t predict who would lose weight. However, when researchers combined genetic information with starting weight and body composition, they created a better prediction tool. The good news: people lost weight regardless of their genetic risk, suggesting that lifestyle changes work for everyone, not just those with “lucky” genes.

The Quick Take

  • What they studied: Whether a person’s genetic makeup (their DNA code related to weight) could predict how much weight they’d lose from diet and exercise
  • Who participated: 145 Japanese adults who completed an 8-12 week program combining low-carbohydrate eating and weight training
  • Key finding: Genes alone didn’t predict weight loss success, but combining genetic information with starting body measurements created a useful prediction tool. Everyone lost weight regardless of genetic risk.
  • What it means for you: You shouldn’t blame your genes if you struggle with weight. Diet and exercise work for people with all types of genetic backgrounds. A personalized approach considering your starting point may help predict your success better than genetics alone.

The Research Details

Researchers looked back at data from 145 people who had completed a weight loss program. They calculated each person’s genetic risk score using 75 different spots in their DNA that scientists previously linked to obesity. They measured everyone’s weight, BMI (body mass index), and body fat before and after the 8-12 week program that combined low-carb eating with resistance training. The researchers then used a special mathematical method called data envelopment analysis to create a new scoring system that combined genetic information with starting measurements to see what best predicted weight loss results.

Understanding what actually predicts weight loss success is important because it helps doctors and nutritionists give better personalized advice. If genes alone determined outcomes, people with high genetic risk might give up. This study shows that’s not the case, which is encouraging for everyone trying to lose weight.

This study looked back at existing data rather than following people forward in time, which is a limitation. The sample size of 145 people is moderate. The study was done in Japanese individuals, so results may not apply equally to other populations. The researchers used established genetic markers from previous large studies, which strengthens the genetic analysis. The program was well-defined (8-12 weeks, specific diet and exercise), making results more reliable.

What the Results Show

All participants lost weight and improved their measurements after the program. When researchers tested whether genetic risk scores alone could predict who lost the most weight, they found no significant connection—genes didn’t determine success. However, when they created a new scoring system combining genetic information with each person’s starting weight and body fat percentage, this combined score strongly predicted how much weight people would lose. This suggests that your starting point matters as much as your genes when predicting weight loss success.

BMI (a measure of weight relative to height) and body fat percentage both decreased significantly in all participants. The fact that weight loss happened across all genetic risk groups suggests that lifestyle interventions work universally. The new combined scoring system was much better at predicting individual results than genetics alone.

Previous research has shown that genes influence obesity risk, but this study adds important evidence that genes don’t determine whether someone can successfully lose weight through diet and exercise. This aligns with other research showing that lifestyle changes can overcome genetic predisposition. The finding that a combined approach works better than genetics alone is relatively novel.

The study only looked at Japanese adults, so results may differ in other populations. It was a retrospective study (looking backward at data) rather than following people forward, which is less powerful. The program was relatively short (8-12 weeks), so we don’t know about long-term results. The study didn’t include a control group that didn’t do the program, so we can’t be completely certain the program caused the weight loss. The sample size of 145 is moderate, not huge.

The Bottom Line

If you’re considering a weight loss program, don’t let genetic risk scores discourage you. The evidence suggests diet and exercise work regardless of genetic background. A personalized approach considering your current weight and body composition may help set realistic expectations. Moderate confidence: This study provides good evidence for the general population, though more research is needed.

Anyone concerned about weight loss or worried that their genes make weight loss impossible should find this encouraging. People with family histories of obesity may especially benefit from knowing that lifestyle changes work across all genetic risk levels. Healthcare providers may use this information to give more personalized counseling.

This study showed results in 8-12 weeks, which is a reasonable timeframe to see meaningful changes. However, sustainable weight loss typically requires ongoing lifestyle changes beyond the initial program period.

Want to Apply This Research?

  • Track weekly weight and body measurements (waist circumference, body fat percentage if available) alongside diet adherence and exercise minutes. This creates a personalized baseline similar to what the study used for prediction.
  • Start a combined program of moderate carbohydrate reduction and regular resistance training (2-3 times per week). Log your starting measurements and track progress weekly to see your personal response pattern.
  • Create a 12-week tracking dashboard showing weight, body fat percentage, and exercise consistency. Compare your actual results to initial predictions to understand your personal response to lifestyle changes.

This research suggests that genetic risk scores alone don’t predict weight loss success, but individual results vary. This study should not replace personalized medical advice from your doctor or registered dietitian. If you have underlying health conditions, take medications, or have concerns about starting a diet and exercise program, consult with a healthcare provider first. Results from this Japanese population study may not apply equally to all ethnic groups. Weight loss is complex and involves genetics, behavior, environment, and health conditions—this study addresses only one piece of that puzzle.