Why composition should take the place of weight.
The new addition to potboilers of how to lose 30 lb in 3 weeks or the one month cure for your risk of heart attack is that changing weight and complications of cardiovascular disease ride together.(1) As grabbers go, this is a winner and it could be the source of serious misunderstanding. It is not a mistake or fanciful finagling with numbers. The observation is real. It is meaningful. It raises a very important question about weight loss and diets but in no way suggests that lifestyle changes with weight loss in mind are bad.
Background
Obesity is the problem for all seasons, linked to high blood pressure, diabetes mellitus, elevated cholesterol, sleep apnea as well as heart failure, atrial fibrillation and heart attack. The link to cardiovascular disease is such that body weight often takes center stage in efforts to treat illness.(2) From the association between body weight and the known risk factors for cardiovascular disease come estimates of the value of weight loss. Lose weight and blood pressure is easier to control. Risk factors improve. Therefore, it seems logical that virtually any effort that safely reduces body weight while maintaining essential nutrition is going to be valuable but there is a problem. A consistent observation from efforts to improve the lot of people with cardiovascular disease is that people with disease, who are on average heavier fare better over time.(3) The observation that heavy people get sick but sick, heavy people do better over time is referred to as the obesity paradox. When this thorny observation first attacked logic, a variety of explanations were offered but as yet, no one really knows why it is true, just that it is. Even faced with the paradox, most physicians do not question the need to reduce body fat when its known effects may be fueling identified vascular disease. However, it is possible that weight loss efforts may not provide the benefit that is expected of them. Specific regimens may lower weight without reducing fat. Worse, many diet and exercise regimens designed to address body weight often have brief success, only to see weight return, likely as fat.
Question
In people left to their own designs, does weight that is frequently changing correspond to any difference in the chance of having a heart attack or other problems related to cardiovascular disease.
Study
The source of information was a study done to record heart attacks and complications of cardiovascular disease in more than 9500 people testing different doses of a cholesterol-lowering medication. What the investigators did with the information was to pay attention to something that is usually ignored, how much body weight changed each time it was measured during the study.(1) Over a period of several years, most participants had some variation in weight from visit-to-visit. In about 10-15% of people, the weight swings averaged more than five pounds for each visit. The swingers had an increased risk of complications even when all other things were taken into account. There were several methods of describing how much weight varied between visits. Regardless of how the difference was portrayed, people whose visit-to-visit weight varied more than others, not just in one direction but the amount that it swung in either direction, had a greater chance of encountering difficulty.
Impact/Analysis
The study discovered an association between changing weight and complications but it couldn't address the next question. Why? Did one cause the other or are they just two faces of some other underlying problem? There is no way to tell from the information available. The set up above would suggest that the answer is obvious, dietary recidivism changes body composition to more fatty over time driving vascular disease. However, as often as not, the obvious answer proves to be wrong when put to the test. While we wait for more information, the things to think about are, pay more attention to your waistline than your weight. One of the problems with something like obesity is to make it into a number. Exactly what does it mean to be fat? Is it too much weight, too much weight for age, for height or both? Your total body weight reflects muscle, bone, organs as well as fluid and fat. Changes in weight lasting more than a few days are usually due to a change in either fat or what is referred to as lean body mass. Since your bones and organs are an unusual source of weight change, lean body mass really means muscle. If you diet to lose weight rapidly, there is a good chance that you will lose muscle at the same time. Should the weight later return, there is also a very good chance that what comes back will be fat. While net weight may be the same at the end of some time period, cycling weight change may shift body composition from muscle to fat. If you have vascular disease and lose muscle or gain body fat your chance of having complications of your disease is increased.(4, 5) Researchers examining diets and weight loss have used body composition or more importantly change in body fat to describe the impact of diets and exercise regimens for many years. The easiest method to measure a change in body fat is to use the skin folds around the belly, on the arms, back and elsewhere. For you and I, the easiest measure is the waistline. If it's shrinking, slowly and on purpose, any change in diet and activity is probably helping, even if weight hasn't changed greatly. An effort to lose body fat should be a permanent change of habit. Diet and exercise designed to keep muscle mass and lose fat is almost certainly beneficial. The lesson suggested by the new observations is that attempts to change body composition and weight secondarily should have goals set over six months to years with interventions that are long lasting, if not permanent. Does the type of diet or exercise influence the type of weight that is lost? In addition to seeking some evidence to show why changing weight and increased risk go together, my questions are, 1. What diet/exercise combination best sustains muscle while reducing fat? a. Generally b. In specific groups with physical limitations 2. Is there a rate of intentional, guided weight loss, targeting fat, at which muscle is sacrificed? Stated differently, if you're trying to lose fat and are losing weight, can the speed that it is coming off warn you that you may be losing muscle too? The worst possible conclusion to draw from this study is that a change in lifestyle geared to losing weight is bad. The goal remains laudable when the approach is a long-term change with a goal of reducing body fat but maintaining muscle.
Keywords: Obesity, Diet, Heart Attack, Weight loss
http://www.nejm.org/doi/full/10.1056/NEJMoa1606148
1. Bangalore S, Fayyad R, Laskey R, DeMicco DA, Messerli FH, Waters DD. Body-Weight Fluctuations and Outcomes in Coronary Disease. New England Journal of Medicine. 2017;376(14):1332-40.
2. Poirier P, Giles TD, Bray GA, Hong Y, Stern JS, Pi-Sunyer FX, et al. Obesity and Cardiovascular Disease: Pathophysiology, Evaluation, and Effect of Weight Loss. Circulation. 2006;113(6):898.
3. Romero-Corral A, Montori VM, Somers VK, Korinek J, Thomas RJ, Allison TG, et al. Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies. The Lancet. 2006;368(9536):666-78.
4. Allison DB, Zannolli R, Faith MS, Heo M, Pietrobelli A, VanItallie TB, et al. Weight loss increases and fat loss decreases all-cause mortality rate: results from two independent cohort studies. Int J Obes Relat Metab Disord. 1999;23(6):603-11.
5. Santanasto AJ, Goodpaster BH, Kritchevsky SB, Miljkovic I, Satterfield S, Schwartz AV, et al. Body Composition Remodeling and Mortality: The Health Aging and Body Composition Study. The Journals of Gerontology: Series A. 2017;72(4):513-9.
