When we talk about living longer, it is easy to focus on lifespan: simply adding more years to your life.
But there is another question that may matter just as much: how many of those years will you spend feeling well, staying active and free from major disease or disability?
That is the idea behind healthspan, the portion of your life spent in good health.
Recommended Reading: Healthspan vs Lifespan: Why the Difference Matters
Excess body fat is linked to many conditions that can affect healthspan, including type 2 diabetes, cardiovascular disease, certain cancers, osteoarthritis, obstructive sleep apnoea and fatty liver disease. So it is understandable that weight management has become an important part of preventive health.
But there is an important distinction to make: Weight loss does not automatically result in better health.
What matters is how the weight is lost, what happens to your muscle and fitness along the way, whether the weight stays off, and where you are in life.
The evidence is more nuanced than simply saying, “losing weight is good”. So, what does the research actually tell us?
Is weight loss linked to living longer?
This is one of the areas where the research can initially seem confusing.
Some observational studies have found that people who lose weight have a higher risk of dying. But there is an important problem: these studies often cannot tell whether someone chose to lose weight or whether they lost weight because they were already becoming unwell.
A systematic review and meta-analysis found that unintentional weight loss was associated with a higher risk of all-cause mortality among people, and there was no protective effect found in people who were overweight or obese for unintentional weight loss.
Does this mean that losing weight can increase our chance of dying? The answer lies with the key word: “unintentional” weight loss. When people are losing weight “unintentionally” it could be due to underlying conditions such as cancer, thyroid dysfunction, diabetes, chronic infections, inflammatory diseases, frailty and mental health conditions such as depression. These conditions are associated with an increased risk of dying (mortality).
Thus this result is sometimes referred to as reverse causation: rather than weight loss causing poorer health, declining health may be causing the weight loss.
Randomised controlled trials give us a different perspective because researchers can deliberately assign people to a weight-loss intervention, thus more clearly investigating the link between cause (intentional weight loss) and effect (death).
A 2015 meta-analysis pooled together 15 randomised controlled trial studies involving a total of 17,186 participants, with follow-up ranging from 18 months to 12.6 years. The researchers found that people in the weight-loss groups had a 15% lower risk of all-cause mortality.
Other analyses have found that the potential benefit is clearest among people living with obesity who already have cardiometabolic risk factors. For people who are simply overweight and otherwise metabolically healthy, the evidence is much less clear.
The question should not simply be, “I’m heavy. Should I be losing weight?”
A better question is: “What is my overall metabolic health, and would losing weight intentionally meaningfully improve it?”
Fitness may matter as much as (or more than) the number on the scale
Weight is only one part of your health picture.
A 2021 review examined the relationship between obesity, cardio-respiratory fitness (CRF) or physical activity (PA) and health outcomes. It found that most cardiometabolic risk factors associated with obesity can be improved by exercise training, independent of weight loss. It also found that increasing CRF or PA is associated with more reduction in mortality risk than intentional weight loss alone.
This is important in how we think about weight management. You do not need to lose a certain number of kilograms before exercise “counts” because your fitness is valuable in its own right.
That means a health-focused approach should not prioritise rapid weight loss at the expense of physical activity. In some cases, losing weight through severe calorie restriction while becoming less active could move you further away from the outcome you actually want.
What has the GLP-1 era taught us about weight loss?
The arrival of GLP-1 receptor agonists and related medications has given researchers some of the strongest evidence yet about the relationship between weight loss and health outcomes.
One of the landmark studies is SELECT published in 2024, which included more than 17,600 overweight or obese adults with established cardiovascular disease, but without diabetes.
In this SELECT trial, one of the GLP-1 RA medications investigated reduced major adverse cardiovascular events by 20% compared with placebo. Participants receiving this GLP-1 RA medication also experienced substantially greater weight loss, with a mean reduction in weight of 10.2%, compared with 1.5% with placebo after four years.
But one of the most interesting findings came later.
A prespecified analysis of SELECT published later in 2025 found that the cardiovascular benefit was not simply explained by how much weight people lost.
There was no straightforward linear relationship between early weight loss and later cardiovascular risk. The researchers found that the protective effect of this GLP-1 RA medication on the heart to lower major cardiovascular events was independent to how fat the study participants were at baseline (baseline adiposity), and also independent to how much weight they lost, which suggests that there are some mechanisms from the medication that benefits cardiovascular health beyond fat loss.
So perhaps the more useful way to think about these medications is not simply as weight-loss medications, but as part of a broader strategy to improve metabolic and cardiovascular health.
But what happens to your muscles?
There is an important caveat. When you lose weight, you do not only lose fat. Some of the weight lost can come from lean tissue, including muscle, bone and organs. A systematic review and network meta analysis that looked at 22 randomised controlled trial studies found that GLP-1 RA treatment significantly reduced body weight, but also lean mass, with lean mass loss comprising approximately 25% of the total weight loss.
For someone who starts with a healthy amount of muscle, this may be manageable. For an older adult with limited muscle reserve, however, losing a meaningful amount of muscle could affect strength, mobility and independence.
That is why how you lose weight matters.
Evidence and clinical guidance increasingly point towards combining weight-loss treatment with:
- Adequate protein intake
- Regular resistance training
- Aerobic activity
- A balanced, nutrient-dense diet
Therefore, if you are losing weight, protecting your muscle should be part of the plan and not just an afterthought.
Recommended Reading: How much protein do you actually need?
Why weight loss looks different as you get older
For older adults, the conversation becomes even more nuanced.
As we age, maintaining muscle and bone becomes increasingly important. Losing excess fat may improve health, but losing too much muscle or bone at the same time can affect strength, mobility, bone fracture risk and independence.
A landmark study published in 2011 looked at 107 adults aged 65 and older with obesity. Participants were randomised to control, diet alone, exercise alone, or a combination of diet and exercise for one year.
The combination of diet and exercise produced the strongest improvements in physical function.
Physical performance improved by around 12% with diet alone and 15% with exercise alone, compared with 21% when diet and exercise were combined.
More importantly, the researchers could see the trade-off between losing weight and losing lean tissue.
Lean body mass fell by around 5% with diet alone compared with a decrease of 3% with diet plus exercise. Lean body mass increased by 2% in the group with exercise alone.
Hip bone mineral density fell by 2.6% with diet alone versus 1.1% with diet plus exercise. In contrast, the exercise-only group gained 1.5% in bone density.
What this means is that for older adults, weight loss should not be considered successful simply because the scales go down. What matters is what happens to strength, physical function, muscle and bone. In this stage of life, preserving the ability to climb stairs, carry groceries, get up from a chair and remain independent may be far more meaningful than losing another few kilograms.
Thus it is even more important in the older age group to manage weight loss properly, with a balanced dietary and exercise approach, to preserve lean body mass, bone mineral density, and physical function, and optimize for healthy aging.
So, what does all of this mean for your healthspan?
Taken together, the evidence points towards a broader definition of successful weight management.
1. Look beyond your weight
Weight is just a piece of the puzzle. Your blood glucose, blood pressure, cholesterol, fitness, waist circumference, muscle mass and overall metabolic health can all tell you more about your health than the number on the scales alone.
2. Make fitness part of the plan
Exercise is not simply a tool for burning calories. Building cardiorespiratory fitness and strength can independently improve your health and help protect your body while you lose weight.
3. Protect your muscle
Whether weight loss comes from dietary changes, medication or surgery, some lean tissue may be lost along the way. Adequate protein and resistance training can help make the weight you lose more meaningful, by helping you lose more fat while preserving the muscle you need for strength and function.
4. Prioritise sustainability
Rapid weight loss can be appealing, but repeatedly losing and regaining weight may not be the outcome you want. The best approach is one that you can maintain as part of your life.
5. Change the goal as your needs change
What is appropriate at 35 may not be appropriate at 75. For older adults especially, preserving lean mass (muscle and bone) and physical function may matter more than achieving a particular number on the scale.
6. Remember that weight loss is not the whole story
The SELECT trial provides an important reminder that some of the health benefits associated with modern weight-loss medication may not be explained by weight loss alone. Your cardiovascular and metabolic health is influenced by much more than your weight.
Limitations of the evidence
It is important to recognise that science is still evolving. Much of the mortality research involves follow-up periods of several years rather than the decades that define a person’s full healthspan. Meta-analyses of intentional weight loss also differ depending on which studies are included and how intentional weight loss is defined.
Most randomised weight-loss trials have focused on adults with obesity (BMI ≥30), so the evidence is less robust for people in the overweight range.
And while research into GLP-1 medications and muscle preservation is developing rapidly, much of the available evidence is recent. We do not yet have 10-year or longer-term body-composition data for these medications.
So, rather than looking for one definitive answer to whether weight loss is “good” or “bad”, it may be more useful to ask: Good for whom, achieved how, and with what impact on the rest of the body?
What could your next step look like?
Your healthspan is built over time. Whether your priority is managing your weight today or understanding your long-term health risks, the right starting point depends on where you are now.
If weight management is your priority
If you’re struggling to lose weight or keep it off, you don’t have to navigate it alone. NOVI Weight Care combines doctor-led medical treatment with personalized nutrition and lifestyle coaching, body composition tracking and ongoing support through the NOVI App.
If you’re thinking about your long-term health
Your weight is only one part of the healthspan picture. NOVI Longevity helps you take a more proactive look at your health through personalised assessments, targeted testing and medical guidance so you can better understand where you are today and what you can do to support your health for the years ahead.
This article is for general educational purposes and summarises published research. It is not medical advice and does not substitute for individualised guidance from a physician, particularly regarding medication use, bariatric surgery candidacy, or exercise prescriptions in older or medically complex adults.