Researchers studied 71 people with obesity who followed a strict diet for 8 weeks to see how weight loss affects heart and blood vessel health. The study found that even modest weight loss—about 7 pounds—improved how well blood vessels work and lowered blood pressure, especially in people whose hearts were already struggling. Interestingly, people with slightly better heart health before the diet showed different improvements, with their nervous system becoming more relaxed. These findings suggest that quick weight loss through dieting can help your heart work better relatively fast, though the benefits appear differently depending on your starting heart health.

The Quick Take

  • What they studied: Whether losing weight through a strict diet for 8 weeks could improve how well blood vessels work and reduce stress on the heart in people with obesity
  • Who participated: 71 adults between ages 40-70 with obesity (BMI of 30 or higher). They were split into two groups: 44 with moderate heart health and 27 with low heart health
  • Key finding: Both groups lost similar amounts of weight (about 7 pounds), but the improvements in heart function differed. People with low heart health saw their blood pressure drop and blood vessels work better. People with moderate heart health showed their nervous system became more relaxed and less stressed
  • What it means for you: If you have obesity and heart concerns, losing weight through dieting may help your heart function improve within weeks. However, the specific benefits depend on your current heart health status. Talk to your doctor before starting any strict diet, as 800 calories per day is quite low

The Research Details

This was a short-term study where researchers carefully measured how people’s hearts and blood vessels changed after following a very strict diet. Seventy-one people with obesity participated, and they were divided into two groups based on their starting heart health. Everyone ate 800 calories less per day than they normally would for 8 weeks straight.

The researchers used special equipment to measure three important things: how hard the heart was pumping (central blood pressure), how well the nervous system was working (heart rate variability), and how well tiny blood vessels in the skin could expand and contract (microvascular function). They took these measurements before the diet started and again after 8 weeks ended.

The study was designed to see if weight loss alone—without exercise or medication changes—could improve these heart-related measurements in a short time period.

Understanding how quickly weight loss affects heart function is important because many people want to know if dieting will actually help their heart health. This study looked at real, measurable changes in how the heart and blood vessels work, not just weight on a scale. By measuring these changes in just 8 weeks, researchers could see if improvements happen fast enough to motivate people to stick with a diet

This study has some strengths: it measured actual physical changes in the heart and blood vessels using specialized equipment, not just asking people questions. The researchers were careful to divide people into groups based on their starting heart health. However, the study is relatively small (71 people) and short (8 weeks), so results may not apply to everyone. The diet was very strict (800 calories less per day), which some people might find hard to follow long-term. There was no control group eating normally for comparison, which would have made the results stronger

What the Results Show

Both groups of people lost similar amounts of weight during the 8 weeks—about 3 pounds on average. However, the heart improvements were different between the two groups, which was surprising.

People with low heart health at the start saw their central blood pressure (the pressure in the main artery from the heart) drop from 113 to 109 mmHg. This may not sound like much, but even small drops in blood pressure can reduce heart disease risk. They also showed that their tiny blood vessels in the skin could expand better after being squeezed, which suggests their overall blood vessel function improved.

People with moderate heart health showed different benefits. Their heart rate became slower and more relaxed (the time between heartbeats increased from 933 to 994 milliseconds), and their sympathetic nervous system—the part that creates stress and tension—became less active. This means their body was in a more relaxed state overall.

These different results suggest that weight loss helps the heart in different ways depending on how healthy your heart was to begin with.

The researchers found interesting connections in the low heart health group: people whose blood vessels improved the most also showed the biggest drops in a measure of artery stiffness (pulse wave velocity) and the biggest reductions in nervous system stress. This suggests that for people with struggling hearts, weight loss helps multiple heart systems at the same time. The moderate heart health group didn’t show these same connections, indicating their bodies responded to weight loss differently

Previous research has shown that weight loss helps heart health, but most studies looked at larger weight losses over longer periods or included exercise. This study is notable because it shows that even modest weight loss (about 7 pounds) from diet alone can improve heart function in just 8 weeks. The finding that different groups of people see different benefits is relatively new and suggests that one-size-fits-all heart health advice may not be best. Earlier studies didn’t always separate people by their starting heart health level, which may be why this study found more specific results

The study only lasted 8 weeks, so we don’t know if these improvements continue longer or if people can stick with such a strict diet. The diet was very low in calories (800 calories less per day), which is more extreme than typical weight loss diets and might not be safe or realistic for everyone. The study didn’t include a comparison group of people eating normally, so we can’t be completely sure the diet caused the improvements versus other factors. The group was relatively small and mostly included middle-aged and older adults, so results might be different for younger people or different ethnic groups. Finally, the study didn’t measure whether people actually felt better or had fewer heart problems—only that measurements on machines changed

The Bottom Line

If you have obesity and heart health concerns, modest weight loss through diet may improve your heart function within weeks (moderate confidence). However, the 800-calorie reduction used in this study is quite strict and should only be done under medical supervision. A more moderate calorie reduction (300-500 calories per day) combined with exercise is usually safer and more sustainable. People with low heart health may see blood pressure and blood vessel improvements, while those with moderate heart health may see nervous system benefits. Always consult your doctor before starting any weight loss diet, especially if you have heart problems

This research is most relevant for adults aged 40-70 with obesity who have concerns about their heart health. If you have been told you have poor cardiovascular health or moderate cardiovascular health, these findings suggest weight loss might help. However, people with very serious heart conditions should talk to their cardiologist before dieting. This study may be less relevant for younger people, those without obesity, or people with excellent heart health. Anyone considering the 800-calorie diet used in this study should absolutely get medical approval first, as it’s quite restrictive

Based on this study, you might see improvements in blood pressure and blood vessel function within 4-8 weeks of starting a weight loss diet. However, these are early changes measured by machines—you may not feel different yet. Real-world benefits like having more energy, better exercise tolerance, or fewer heart symptoms typically take longer. Expect to see sustained improvements over 3-6 months of consistent weight loss. Remember that maintaining weight loss long-term is harder than losing it initially, so focus on changes you can stick with

Want to Apply This Research?

  • Track daily calorie intake and weekly weight loss (aim for 1-2 pounds per week rather than the 800-calorie deficit used in this study). Also track resting heart rate weekly—a decreasing resting heart rate suggests your heart is becoming healthier and more efficient
  • Use the app to set a realistic calorie reduction goal (300-500 calories less per day is more sustainable than 800), log all meals and snacks, and set reminders for meal times. Include a weekly check-in to assess how you’re feeling—energy levels, mood, and any heart-related symptoms—not just the number on the scale
  • Measure and log resting heart rate every morning before getting out of bed. Track blood pressure weekly if you have a home monitor. Note any changes in how you feel during daily activities. Set monthly goals for weight loss (4-8 pounds per month is healthy) and schedule check-ins with your doctor every 4-8 weeks to ensure the diet is safe and working for you

This research describes findings from a short-term, supervised study using a very strict diet (800 calories per day reduction). Before starting any weight loss diet, especially one this restrictive, consult with your doctor or registered dietitian. This is particularly important if you have heart disease, take blood pressure medications, or have other health conditions. The findings suggest potential benefits but do not replace personalized medical advice. Results may vary significantly between individuals based on age, overall health, medications, and other factors. This article is for educational purposes and should not be used to diagnose or treat any medical condition.