Scientists studied 242 adults with insulin resistance (a condition where the body struggles to use sugar properly) to see if a new health score could help predict which diet works best for losing fat. Participants followed either a low-fat, high-protein diet or a diet rich in healthy oils for 12 weeks. The researchers found that people in better overall health lost more fat when they followed the diet matched to their body type, while people in poorer health lost similar amounts of fat on either diet. This suggests that a personalized approach using both a health score and body type information could help people choose the most effective diet for their situation.

The Quick Take

  • What they studied: Whether a new health score combined with information about how someone’s body handles insulin could help predict which diet would work best for losing fat
  • Who participated: 242 adults between ages 40-75 who had insulin resistance (difficulty processing sugar). About 184 completed the full study. Participants were randomly assigned to follow one of two different diets for 12 weeks
  • Key finding: People in the best health category lost more fat when they followed a diet matched to their specific body type. People in the worst health category lost similar amounts of fat on either diet, suggesting one-size-fits-all approaches might work better for them
  • What it means for you: If you have insulin resistance and are trying to lose weight, getting personalized information about your health status and body type might help you choose a diet that works better for you—but this is still early research and should be discussed with your doctor

The Research Details

This was a randomized controlled trial, which is considered one of the strongest types of research. Scientists took 242 adults with insulin resistance and randomly divided them into two groups. One group followed a low-fat diet that was high in protein and fiber, while the other group followed a diet rich in monounsaturated fats (the healthy kind found in olive oil and nuts). Both diets had the same number of calories. Everyone followed their assigned diet for 12 weeks.

The researchers also created a new scoring system called the MetaboHealth score that measures overall health by looking at risks for serious conditions like heart disease, weakness in old age, and memory problems. They grouped participants into three categories based on this score: the healthiest third, the middle third, and the least healthy third.

At the beginning and end of the study, researchers measured how well participants’ bodies handled sugar (using a glucose tolerance test) and measured their body fat using a special scanning machine called a DXA scan. This allowed them to see exactly how much fat people lost and where on their body the fat came from.

This research approach is important because it goes beyond just testing whether a diet works—it tries to figure out which diet works best for which person. Many people struggle with weight loss because they’re following a diet that might work great for someone else but not for them. By combining information about someone’s overall health status with their body type, doctors and nutritionists might be able to make better recommendations

This study has several strengths: it was randomized (reducing bias), it included a decent number of participants, it measured actual body composition with precise equipment rather than just weight, and it lasted long enough to see real changes. However, 58 people dropped out or didn’t complete the study, which is fairly common. The study only lasted 12 weeks, so we don’t know if results would continue longer. The findings were published in a respected journal focused on obesity research

What the Results Show

The main finding was about how fat loss worked differently depending on people’s health status. For people in the healthiest third of the group, the diet that matched their specific body type (whether their insulin resistance was in their muscles or liver) led to noticeably more fat loss. This suggests that personalization really matters for people in good health.

Interestingly, for people in the least healthy third, both diets worked about equally well for fat loss. This means that for people with more health problems, it might not matter as much which specific diet they choose—they’ll lose similar amounts of fat either way.

The researchers also looked at different types of fat loss: fat around the belly area (android fat), fat around the hips and thighs (gynoid fat), total body fat percentage, and a measurement called fat mass index. All of these showed similar patterns—better results with matched diets in healthier people, similar results in less healthy people.

One important note: the MetaboHealth score itself didn’t change much over the 12 weeks, suggesting that while it’s useful for predicting outcomes, these diets didn’t dramatically improve overall health markers in this short timeframe

The study looked at cardiometabolic outcomes (measurements related to heart and metabolic health like blood sugar control), but didn’t find significant differences based on the combination of health score and body type. This suggests that while personalized diets help with fat loss, they might work through different mechanisms than improving blood sugar control in the short term

Previous research from the same team had already shown that different body types respond better to different diets—some people’s insulin resistance is mainly in their muscles while others’ is mainly in their liver. This new study builds on that by adding another layer: overall health status. It suggests that the personalization approach might need to be even more detailed, taking into account not just body type but also general health condition

The study only lasted 12 weeks, so we don’t know if these patterns continue over months or years. About 24% of participants didn’t complete the study, which could affect the results. The study included only people aged 40-75 with insulin resistance, so results might not apply to younger people or those without this condition. The study was relatively small (184 people with complete data), so some findings might not hold up in larger groups. The researchers didn’t find the interactions they expected for blood sugar control, which suggests the picture might be more complicated than the theory predicted

The Bottom Line

If you have insulin resistance and are trying to lose weight, talk to your doctor or registered dietitian about getting personalized recommendations based on your specific health profile and body type. While this research is promising, it’s still early-stage, and personalized nutrition should be guided by a healthcare professional. The evidence suggests that matching your diet to your body type may help, especially if you’re in good overall health (moderate confidence level)

This research is most relevant for middle-aged and older adults (40-75) who have been diagnosed with insulin resistance and are trying to lose weight. People in better overall health may benefit more from personalized diet matching. People without insulin resistance or those under 40 should consult their doctor about whether these findings apply to them. This is not medical advice and shouldn’t replace conversations with your healthcare provider

In this study, measurable fat loss occurred within 12 weeks, but the MetaboHealth score didn’t change significantly in that timeframe. Realistic expectations are that you might see fat loss changes within 8-12 weeks, but improvements in overall health markers might take longer. Individual results will vary based on your starting point and how well you stick to the diet

Want to Apply This Research?

  • Track weekly body measurements (waist, hip, and chest circumference) and take progress photos every 2 weeks, as these may show fat loss changes before scale weight changes. Also log which diet type you’re following and rate your adherence daily (1-10 scale)
  • If you have insulin resistance, work with your healthcare provider to determine your body type, then use the app to track meals that match your personalized diet recommendation. Set reminders for meal prep and log your meals to maintain consistency with your assigned diet plan
  • Track fat loss progress through body measurements and photos rather than just weight. Monitor energy levels, hunger patterns, and how well you’re sticking to your diet. Check in with your doctor every 4-6 weeks to assess progress and adjust if needed. Note any changes in blood sugar readings if you monitor those

This research is informational only and should not replace professional medical advice. If you have insulin resistance or are considering making significant dietary changes, consult with your doctor or registered dietitian before starting any new diet plan. This study was conducted over 12 weeks in a controlled setting; individual results may vary. The MetaboHealth score is a research tool and not yet available for general clinical use. Always discuss personalized nutrition strategies with your healthcare provider, especially if you have existing health conditions or take medications