Is 64 the right number?

The Robert Wood Johnson Foundation (RWJF) released a report today that suggests children need to reduce their caloric intake or increase their expenditure by an average (and not individual) amount of 64 calories or face a future where they are heavier by 4 pounds than the cohort that went before them.

WHEW:

Meaning that around 16% of adolescents were obese in 2007-08 and if things don't change, the obesity rate will rise to 20% for year 2020. 

Things must change - this is not an acceptable outcome.

Children who are obese tend to remain obese and the consequences of obesity across a life span are significant and disabling. 

Whether or not '64' is the magic number is questionable.  It is derived from population wide averages - meaning it looks at the weights of children in aggregate and finds the average number that all kids would have to lower to prevent the rise in obesity for the group.  However, some children are already obese and would have to lose weight before sustaining it (meaning a 100+ calorie deficit), and some children are NOT overweight (meaning a 0 calorie deficit).

Non white girls are heavier than white girls and boys are generally less heavy than girls.  Living in a poor neighborhood also increases the risk of obesity - i.e. living in a food desert that lacks access to affordable, lower calorie foods.

That being said - what is 64 calories?  It is easier to quantify as intake because expenditure depends on ones body weight, fitness, and intensity of exercise - so we really can't say -for instance, 63 cals= a 30 minute walk.  We can say how much 64 calories is in food.  For example, it is one and a half teaspoons of oil or pats of butter.  It is the extra calories in 2% vs skim milk.  Calories could easily be reduced if SSBs were cut out of schools (as RWJF suggests - NO SODA). 

Calories and Diets in the Lab

I was reading an article earlier this week which referred to the research referenced at the end of this post.  I was curious about the study because it compared the weight loss results of three or four groups.  I searched for the study itself so that I could see the actual requirements for each of the groups.  Here are the 4 categories that intrigued me:

1. Consume 25% Less Calories per day
2. Consume 12.5% Less Calories per day and Increase Physical Activity by 12.5%
3. Consume a Very Low Calorie Diet (VLCD)
4. Consume as usual (control group)

Instead of going too much into the study, I want to share what these group assignments  meant for the people involved in the research. I think the information is relevant and interesting to people who "cut their calories."  Ironically, it was the VLCD group that got my attention.  The article I was reading mentioned 25% and 12.5% reductions but did not give any clue as to what was meant by very low calorie. 

The scientists were able to determine the near exact total energy expenditure (TEE) and total energy intake (TEI) of the participants when they signed up for the project.  This was a small study.  The participants stayed overnight (once or twice) in the lab and ate all their meals according to a strict protocol in the weeks that followed (except the control group).  Each of the reduced calorie groups had a different caloric plan, based on their individual baseline and metabolic (energy burn) needs.   

For the purpose of an example, let us say that the TEI of a person in group 1 was 1900 calories at the start of the study. That means they would then eat 475 calories less (25%)or 1425  calories a day.  I believe the person did this until they lost a certain amount of body weight and then the calories were adjusted in order to maintain the new weight.  It could be that the end caloric intake was 1600 a day.
Take a similar person in group 2.  They would eat about 235 calories less than 1900 and would have to burn the other 240 calories in exercise.  The heavier a person is, the less time they would need to burn those calories, but according to the article, the average time spent walking (or something similar) per day was between 45 and 50 minutes.  This group had to exercise 5 days a week and 3 of those days had to be under the supervision of a research assistant.
Group 3 got the worse of it to be sure.  They were given 890 calories a day until they lost 15% of their body weight.  After which, whatever calorie amount was needed to maintain their new weight was adopted.
So - all this to say that in the 24 weeks for which results are provided up until week 24 when groups 1 and 2 merged, the diet only group lost more weight than the diet and exercise group.  
The VLCD group -the 890 folks- lost the most weight and lost it the fastest, but it is unrealistic for ANYONE in a "free living" environment to manage a diet that extreme. I would not have known if the VLCD was feasible if I had not tracked down the study protocol. 

If you are interested in the study, the information to access it is below.

Effect of 6-Month Calorie Restriction on Biomarkers of Longevity, Metabolic Adaptation, and Oxidative Stress in Overweight Individuals: A Randomized Controlled Trial
Leonie K. Heilbronn, Lilian de Jonge, Madlyn I. Frisard, JAMA. 2006;295(13):1539-1548.

What Physical Activity Can Do

I had the opportunity to attend a lecture  conducted by a scientist from the University of Pittsburgh today.  He studies the impact of physical activity/exercise on weight loss and conditions related to obesity (diabetes, inflammation, HTN, heart disease).  His name is Dr. John Jakicic and he has had numerous studies published in peer reviewed science journals.  IN fact, I recall having read some of the studies that he referenced today.

I went to the lecture to see if he would present anything to support or challenge my assertions.  In case you have forgotten my stance (which developed from reading a lot of research), it is this:
Physical activity is very important and effective in reducing disease occurrence, in preventing adverse outcomes due to a disease, in promoting successful or active aging and for managing moods - or mental health.  It assists in weight loss and weight maintenance, but is not the best strategy for weight loss on its own.  Physical activity is associated with significant weight loss only in the presence of caloric reduction or restriction.  I.e. eating less.  

Before we get into that - let me be very clear that exercise can improve health even in the absence of weight loss and even in persons who are obese.  Obese persons who exercise are healthier than obese persons who do not.  Obese persons who exercise can have some improvement in risk factors even if they do not lose weight. Let me break that down.  An obese diabetic person who only exercises may not lose weight, but research supports that exercise alone can improve their blood sugar (or hemoglobin A1C).  Exercise can moderate blood pressure numbers and reduce inflammation (CRP) that increases the risk for heart attacks.  Exercise alone is helpful. 
Exercise AND weight loss are the best treatments for obesity and overweight.

Dr. Jakicic showed that exercising more than 300 minutes a week (w/out changing the amount of food eaten) led to a 3% weight loss - or about 5 pounds. [that is equal to about ten 30 minute walks a week] He told us that we (exercise and public health professionals) needed to be careful about what we said to people regarding exercise.  We needed to make sure that people maintained realistic expectations. He gave the example of the beginning of a new year when everyone heads to the gym and works out every day but the weight does not come off because they do not also change their eating.  The people have gone to the gym because they think they just have to exercise more and the weight will come off.  When that does not work, they quit the gym.

He actually showed a great chart during his presentation.  The chart had several lines that went from left to right.  The lines represented time one (baseline) and time two and the further the line dropped at time two the more weight the person lost.  Each line represented a different condition.  1)  for just calorie reduction, 2) a line for  exercise > 300 min a week, 3) a line for exercise at ~ 150 min a week, and 4) a line for a combination.  The diet alone line and the combo line were close together (low on the graph) - the others were up high, indicating no or few pounds lost. 
Therefore, as I have said, diet alone is far more powerful than exercise alone for ONE specific thing- losing weight.  Together they are better and best, but singularly they both have a powerful impact on health in general.