Friday, April 27, 2012

Is It the Lifestyle or the Fat?

Tell me if this sounds familiar: person starts an exercise program and changes his/her diet.  After a few weeks or months, he or she loses a noticeable amount of weight.  After seeing the results of the next blood test, the doctor commends the person for major health improvements (for blood glucose, blood pressure, triglycerides, etc.).   

Sounds like a great story...but why did the health markers improve?  Does health improve because of the fat loss or the lifestyle changes (diet and exercise)? 

Obviously they can both be responsible to some extent, but let's determine what the majority cause is.  If you believe fat is the primary determinant of health change, then reducing body fat without a change in lifestyle should make noticeable improvements to health.  If you side with lifestyle, then exercise and diet without weight loss should be very effective in improving health.  I'm going to use those scenarios to answer the question.

Fat Loss Without Lifestyle Change

How does one lose fat without a change in lifestyle?  Liposuction.  An average of 22 lbs. of fat was removed from 15 obese women [1].  Seven of the women had diabetes.  The women were assessed 10-12 weeks after the procedure.

The results: at the assessment period, the non-diabetic women had 20 fewer fat lbs. than their pre-liposuction weight, while the diabetic women went on to lose another pound of fat (totaling 23 lbs. of fat lost).   Diabetic or non-diabetic, the women has no changes in insulin sensitivity, blood pressure, blood glucose, cardiovascular inflammation, or blood lipids ("cholesterol").

Lifestyle Change Without Fat Loss

In regards to exercise, many studies lasting weeks or even months have led to little or no weight loss.  One study put 58 overweight or obese men and women through twelve weeks of aerobic exercise, five times per week [2].  Using the amount of calories expended per session, the researchers predicted a specific amount of weight loss for each individual.  26 of the 58 failed to hit their weight loss predictions.  However, despite losing only about two pounds (versus an average over 10 pounds for the other 32), the 26 that fell short had greater decreases in systolic and diastolic blood pressure.  In another study, overweight women, ages 24-44, strength trained for a year and experienced no change in weight [3].  However, their arteries improved greatly in ability to dilate with increased blood flow, which translates to a decrease in risk for heart disease or stroke.  Overall, without weight loss, both aerobic exercise and resistance training can reduce blood glucose and blood pressure [4].

One study was designed to look at health changes from diet without weight loss [5].  The study examined the effects of a DASH diet on blood pressure without changes in sodium or weight.  The DASH diet stresses a high amount of fruits and vegetables and calories were increased anytime weight was lost from week-to-week.  The study lasted eight weeks and included 459 people.  At the end, subjects with high and normal blood pressures improved (-11.6 and -3.5 mmHg).

The Importance of the Distinction

Why is answering this question important?  Am I just wasting your time by arguing technicalities?  No, not at all.  This is a very important distinction because exercise and a healthy diet fail often in producing the desired amount of weight loss.  In fact, sometimes exercise without a diet change can lead to weight gain.  However, weight change and health improvement are not always linked with each other, and starting an exercise program or adopting a better diet will improve health.  For those of you who don't see the physique changes you seek with a healthier lifestyle, don't quit; you are receiving a much greater benefit: better health.  Don't stress over your weight: focus on your habits.  "Losing a few pounds" and "improving my health" are not synonymous phrases.


Steve Parker, M.D. said...

Very good points, Sean.

The Cooper Clinic in Dallas looked at fitness, fatness, and death over time in men. Here's what they found.

Men live longer if they maintain or improve their fitness level over time.

Part of that improved longevity stems from reduced risk of death from cardiovascular disease (e.g., heart attack and stroke).

Compared with men who lose fitness with aging, those who maintained their fitness had a 30% lower risk of death; those who improved their fitness had a 40% lower risk of death. Fitness was judged by performance on a maximal treadmill exercise stress test.

Body mass index over time didn’t have any effect on all-cause mortality but was linked to higher risk of cardiovascular death. The researchers, however, figured that losses in fitness were the more likely explanation for higher cardiovascular deaths. In other words, as men age, it’s more important to maintain or improve fitness than to lose excess body fat or avoid overweight.


Reference: Lee, Duck-chul, et al. Long-term effects of changes in cardiorespiratory fitness and bodly mass index on all-cause and cardiovascular disease mortality in men. Circulation, 124 (2011): 2,483-2,490

Dr. Sean Preuss said...

Hi Steve,

Great point! We just looked at Lee's study in class about two weeks ago. The point of fat and fit being better than thin and unfit is an important message, especially for those who can't or have extreme trouble losing weight. I realize we are a very aesthetically driven society, but health and longevity should be paramount to a beach body.