What is the real goal of weight loss? In healthcare, reducing excess body fat is known to improve many complications faced by patients with obesity. Even modest to moderate weight loss contributes to improvements in health. Normalizing body weight is not required.
While our culture promotes an ideal body size, in the healthcare setting, our attention must focus on achieving health improvement. We need to be more tolerant of variations in body size if patients are healthy. Of note, varying amounts of weight loss produce improvement in the different complications of obesity, so the amount of weight loss required for improving one condition differs from that required to improve another condition.
When we prescribe weight loss for health improvement, we are trying to reduce both the mechanical burden of fat and the excess ectopic and visceral body fat that is driving disease. The good news about the physiology of weight loss is that we do not need to attain a body mass index (BMI) of 25 or even 30 to have health improvement. The excess abnormal body fat is the first to go!
Losing weight causes a disproportional reduction in ectopic and visceral fat depots. With a 5% weight loss, visceral fat is reduced by 9%. With 16% weight loss, visceral fat is reduced by 30%. Clearing of liver fat is even more dramatic. With 16% weight loss, 65% of liver fat is cleared.
Because ectopic abnormal fat is cleared preferentially with weight loss, it affects different tissues with varying amounts of weight loss.
Weight loss and diabetes. A close relationship exists between weight loss and insulin sensitivity. With just 5% weight loss, insulin sensitivity in the liver and adipose tissue is greatly improved; but while muscle insulin sensitivity is improved at just 5% weight loss, it continues to improve with further weight loss. Indeed, weight loss has enormous benefits in improving glycemia in prediabetes and diabetes.
In patients with impaired glucose tolerance, weight loss of 10% can eliminate progression to type 2 diabetes. In patients with type 2 diabetes who still have beta-cell reserve, 15% weight loss can produce diabetes remission — normoglycemia without diabetes medications.
Weight loss and cardiovascular risk factors. Even very small amounts of weight loss — 3% — can improve triglycerides and glycemia. It takes 5% weight loss to show benefits in systolic and diastolic blood pressure, and in HDL and LDL cholesterol levels. For all of these, additional weight loss brings more improvement. Inflammatory markers are more difficult. It takes 10%-15% weight loss to improve most of these — for example, C-reactive protein .
Weight loss and other complications. It takes 10% or more weight loss to demonstrate improvements in symptoms in obstructive sleep apnea and gastroesophageal reflux disease. For knee pain, the relationship to improvement is not based on achieving a percentage loss. Each pound of weight lost can result in a fourfold reduction in the load exerted on the knee per step during daily activities, but it is important to reduce weight before there is structural damage because weight loss can't repair damaged knee joints. Moderate weight loss (5%-10%) produces improvements in quality-of-life measures, in urinary stress incontinence symptoms, and in measures of sexual function. It probably takes 15% or more weight loss to demonstrate improvement in cardiovascular events.
Must heavier patients lose more weight? To answer this question, it is important to think in terms of percent weight loss rather than pounds or kilograms. In large studies of lifestyle intervention, of course individuals with higher BMI lost more weight. But the percentage weight loss was the same across BMI categories: class 1 (BMI 30-35), class 2 (BMI 35-40), class 3 (BMI >40). Furthermore, the improvement in risk factors was the same across BMI categories. Those with class 3 obesity had the same improvements as those with class 1. This provides further rationale for thinking about weight loss as a percentage from baseline weight rather than as simply a weight-loss goal in pounds.
Goal setting is an important part of any behavioral intervention. At the start of a weight-loss intervention, the healthcare provider should raise the issue of the goal and the time course for achieving it. Patients often have unrealistic expectations, wanting to achieve large amounts of weight loss rapidly. Unfortunately, popular culture has reinforced this idea with advertisements using "Lose 10 pounds the first week" and promoting before-and-after pictures of weight-loss results. The job of the healthcare provider is to coach and guide the patient in terms of achievable weight loss that can bring health improvement, safely. Managing patient expectations is critical to long-term success.
Think in terms of percentage weight loss, not pounds, and set goals at achievable time points. Help patients translate a percent weight-loss goal to a pound's goal at 3, 6, and 12 months. With the emergence of medications approved for chronic weight management with robust weight-loss efficacy, it now is possible to achieve a weight-loss goal of 10% or 15% with regularity, and some patients will be able to achieve 20% or 25% weight loss with newer medications.
We should help our patients set a goal by calculating a goal for certain time points. A good goal for 3 months would be 5% weight loss. For our 200-lb patient, we would translate that to 10 lb in 3 months. For 6 months, the goal should be 10% (20 lb for our 200-lb patient). The usual trajectory of weight loss with lifestyle intervention alone is for a "plateau" at 6 months, although with newer medications, weight loss will continue for more than a year. That 1-year goal might be 15% (30 lb for our 200-lb patient) or even more, based on the patient's baseline weight and body composition.
Weight-loss calculators can be useful tools for patients and healthcare providers. They can be found online and include the National Institutes of Health Body Weight Planner and the Pennington Biomedical Weight Loss Predictor Calculator. These tools give patients a realistic expectation of how fast weight loss can occur and provide guidelines to measure success.
Can patients lose too much weight? In this patient population, losing too much weight is not typically a concern. However, newer medications are achieving average weight losses of 17% and 22% at 62 weeks, as reported on Medscape. There is a wide variation in response to these newer agents which target appetite, and many patients are losing more than the average percentages.
Remembering that the goal of weight loss is the reduction of excess abnormal body fat, we want patients to preserve as much lean mass as possible. Weight-bearing exercise can help during the weight-loss phase, but large or rapid weight loss can be concerning, especially in older individuals. When the BMI drops below 25, we want to watch patients carefully. Measurement of body composition, including bone mineral density, with dual-energy x-ray absorptiometry (DEXA) can help. This is a scenario where dose reduction of antiobesity medication can be indicated, and good clinical judgment is required to keep weight loss at healthy levels.
The future of weight loss. In the past, our strategy has been to promote as much weight loss as possible. With more effective medications, our strategy will have to change to a treat-to-target approach, such as we already use in hypertension and diabetes.
With the ability to produce powerful effects on appetite will come the need to not only target weight loss but to target preservation of lean mass, and even to target different approaches for weight-loss maintenance. At present, we have no evidence that stopping medications results in anything other than weight regain. The study of different approaches to weight-loss maintenance will require our full attention.
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Cite this: How Much Weight Does My Patient Need to Lose? - Medscape - Aug 24, 2022.