Science Summary: Weight Management (Cardio or Weights Part 10)

Before you read, take a look at my post on dieting!  I cover a lot of the practical things there and a lot of the science things here.

This post is a continuation on my series through Alex Hutchinson’s Which Comes First, Cardio or Weights? All of the following questions are taken from this book and the answers are paraphrased from the authors words with my interpretations and thoughts added in.

— Scott

Is it possible to be fat and healthy at the same time?

Short Answer:  Health is more directly correlated with fitness.  It is possible to be healthy and fat as long a you maintain a high level of physical fitness.

Long Answer:  A 2009 study published in the journal Obesity found that overweight subjects had lower mortality rates than people of normal weight.  This caused a minor uproar as the results were surprising to most.   Other research demonstrates that when physical activity level is accounted for, mortality rates of both normal and overweight people are nearly equivalent.  All that being said though, obese people still had higher mortality rates than people of normal weight.  Other factors such as quality of life also tend to be worse for overweight and obese individuals despite comparable length of life.

Is weight loss simply the difference between “calories in” and “calories out”?

Short Answer:  It’s not simple at all, but yes.

Long Answer:  Weight loss happens when your body burns more energy than it is consuming.  For every pound of fat, you need to burn 3,500 calories more than what you are consuming.   It isn’t as simple as that though.  In a 2010 study published in the American Journal of Physiology, researchers found that as participants lost weight their bodies became more efficient and burned less calories doing the same activities.  In a similar study in the Journal of the American Medical Association found participants became less efficient the more they weighed and would burn more calories doing the same tasks than they had when they weighed less.  Moral of the story is that it takes more effort to burn an equivalent amount of calories when you have lost weight.

To lose weight, is it better to eat less or exercise more?

Short Answer:  In terms of weight loss, a calorie is a calorie.  In terms of health, exercising is better than not exercising.

Long Answer:  A 2010 study published in Medicine & Science in Sports & Exercise separated participants into three groups, a control and two at a calorie deficit.  Of the two at a calorie deficit, one was at 25% cut from diet alone and the other was at 12.5% cut from diet and another 12.5% from increased exercise.  Both groups lost approximately 10% of their starting weight over six months and they lost the weight in similar fashions.  The exercising group however showed significant improvements in cardiovascular health, insulin levels, and cholesterol levels.

How can I take advantage of the “fat-burning” zone?

Short Answer:  The “fat-burning zone” is a marketing ploy.  Don’t worry about it.

Long Answer:  While it is true that your body will burn fat over carbohydrates during low intensity exercise, unused carbohydrates are converted to fat anyways.  This was confirmed by a 2010 study at the Garvan Institute of Medical Research in a study where rats were genetically modified to only burn fat.  The rats converted any carbohydrates into fat and then burned the fat stores without any change in net energy.

Won’t exercise make me eat more and gain weight?

Short Answer:  Exercise will make you hungry.  So will cutting calories. Either way, you will be hungry while losing weight until your body adjusts to its new normal.

Long Answer:  Ever since Time magazine ran a story on how one of their journalists couldn’t control his cravings, the myth that exercise will make you gain weight has been making its rounds.  In the 2009 cover story, this journalist wrote about how he would get hungry after exercising and would eat more causing him to gain weight.  Scientific validity aside, his link between exercise and weight gain is a little shaky.  All of that being said, he was right to a degree.  A Harvard University study of  34,000 middle age women of 13 years found that only 13% of participants managed to avoid significant weight gain and these 13% averaged an hour or more of exercise per day.  Weight loss takes serious dedication and work and does not happen accidentally and the Time piece highlights this despite making some sketchy claims.

(Here’s another great time to plug my dieting post where I talk about cheat meals and exercise!)

Can I lose weight while gaining (or maintaining) muscle?

Short Answer:  Gaining? No.  Maintaining?  Yes.

Long Answer:  An ideal cut will shed fat weight while preserving lean body mass.  Several studies have shown that it is essential to maintain at least an average degree of protein consumption in order to maintain muscle mass while losing weight.  A 2010 study by the University of Birmingham suggests aiming for 35% of daily calorie intake to come from protein in order to most effectively maintain muscle mass.

Is lifting weights better than cardio for weight loss?

Short Answer:  It’s uncertain at the moment.

Long Answer:  While cardio has a greater effect in terms of immediate calorie burn, lifting weights potentially increases resting metabolism which increase caloric burn over time.  While there hasn’t yet been conclusive research against the idea, a Korean study found a combination of resistance training and cardio was more effective for weight loss than cardio alone (total number of workouts held constant).

Will I burn more calories commuting by bike or on foot?

Short Answer:  It depends on time and intensity.  You might burn twice as man calories per minute biking but the walk might take three times longer.  Add time or up the intensity to increase calorie burn.

Can I control hunger by manipulating my appetite hormones?

Short Answer:  Yes you can help control hunger, but it won’t affect weight loss.

Long Answer:  There have been several studies showing sleep deprivation increases hunger causing hormones.  Other studies have shown that more frequent meals may suppress hunger causing hormones.  A article published in the British Journal of Nutrition disproved that more frequent meals results in greater weight loss when calories are held constant.

Will sitting too long at work counteract all my fitness gains?

Short Answer:  Not counteract, but it definitely won’t help.

Long Answer:  A 2010 study found that men and women who spent more than 6 hours per day sitting were 18-37% more likely to die over the course of the study than participants who spent more time on their feet.