It’s really true; most of us can’t see the forest for the trees. Medical researchers likewise can’t see the “holistic” for its parts. And the media can’t see diddly — even when their faces are shoved in it. As I’ve said on numerous occasions, I could spend my entire life doing nothing but refuting studies that have little enough value on their own, but when taken out of context by the media, are actually quite misleading…and potentially harmful.
So what are we talking about today?
The “weight loss is difficult” study
A recent obesity study out of Australia1 Priya Sumithran, M.B., B.S., Luke A. Prendergast, Ph.D., Elizabeth Delbridge, Ph.D., Katrina Purcell, B.Sc., et al. “Long-Term Persistence of Hormonal Adaptations to Weight Loss.” N Engl J Med 2011; 365:1597-1604October 27, 2011. <http://www.nejm.org/doi/full/10.1056/NEJMoa1105816> has concluded that when people lose weight, their metabolism automatically slows down and they experience hormonal changes that increase appetite. The researchers theorized that these changes, not portion size, the types of food eaten, or lack of exercise, etc., explain why most dieters so quickly gain back what they lost.
Or to put it in simpler terms; being overweight is not your fault. It’s biology.
The study involved healthy people who were either overweight or obese and were put on a highly restricted diet that caused the subjects to lose at least 10 percent of their body weight. (Note well: exercise was not part of this study.) Unfortunately, and in an apparent surprise to the researchers, the diet caused the participants’ metabolism to slow down and some key weight regulating hormones to change unfavorably. The participants were then kept on a diet designed to maintain their weight loss. A year later, again in what seemed an apparent surprise to the researchers, the participants’ metabolism and hormone levels had not returned to their previous “normal” levels, and they had gained back a substantial portion of what they had previously lost.
Obesity researchers not involved in the study jumped on the results and began speculating that this might be why people find it so hard to lose weight and keep it off. And like a dog in heat, the media was all over it with headlines like:
- Not your fault! Hormones linked to weight regain (Pakistan Observer)2 “Not your fault! Hormones linked to weight regain.”Pakistan Observer. November 06, 2011. (Accessed 6 Nov 2011). <http://pakobserver.net/detailnews.asp?id=122315>
- Hormones make it hard for dieters to stay thin, study indicates (Washington Post)3 Rob Stein. “Hormones make it hard for dieters to stay thin, study indicates.” Washington Post. 25 Oct 2011. (Accessed 5 Nove 2011). <http://www.washingtonpost.com/blogs/the-checkup/post/hormones-make-it-hard-for-dieters-to-stay-thin-study-indicates/2011/10/26/gIQAG9jhJM_blog.html>
- Hormones Make It Hard to Keep Weight Off, Study Says (ABC News)4 Carrie Gann. “Hormones Make It Hard to Keep Weight Off, Study Says.” 27 Oct 2011. ABC News. (Accessed 5 Nov 2011). <http://abcnews.go.com/blogs/health/2011/10/27/hormones-make-it-hard-to-keep-weight-off-study-says/>
- Hunger Hormones Linked to Weight Regain, Study Says (USA Today)5 “Hunger Hormones Linked to Weight Regain, Study Says.” USA Today. 26 Oct 2011. (Accessed 5 Nov 2011). <http://yourlife.usatoday.com/fitness-food/diet-nutrition/story/2011-10-26/Hunger-hormones-linked-to-weight-regain-study-says/50941242/1>
- Hunger Hormones Linked to Weight Regain, Study Says (Fox News.com)6 Associated Press. “Hunger Hormones Linked to Weight Regain, Study Says.” FoxNews.com. 27 Oct 2011. (Accessed 5 Nov 2011). <http://www.foxnews.com/health/2011/10/27/hunger-hormones-linked-to-weight-regain-study-says/>
By the way, did you happen to notice that the headlines from the media all over the world seem to look remarkably similar? There’s a reason for that. The clue can be found in the citation to the Fox News headline (#5). If you follow it back to its source, you’ll see that Fox News mentions that they actually got the report from the Associated Press. Here’s what that means, and it’s something you should keep in mind whenever you see a barrage of headlines touting a study attacking vitamins or antioxidants, for example. The simple truth is that it doesn’t mean that hard charging reporters from a multitude of world renowned media outlets have carefully analyzed and vetted the studies premises, results, or conclusions. Not even close. What happens is that one of the major news services, the Associated Press in this case, picks up the story, asks a couple of non-probing, softball questions of the researchers, calls one or two other “establishment authorities” for commentary, then throws together a newswire that media outlets all over the world pick up. Those outlets then simply rewrite — legally plagiarize — the AP story to make it their own. But they do no further digging or questioning of the study. They simply regurgitate what they’ve been handed. If AP or Reuters or UPI didn’t dig into the study, didn’t challenge it (and they never do), then no one does. That story is now broadcast as unchallenged gospel. Thus, a single, unskilled writer at a news service has the ability to grant blessing to a study (no matter how poorly conceived or executed it may be) and confer authenticity to it all over the world. And many people call that science.
And with that in mind, let’s take a look at the study in question.
The study’s 50 participants were put on an intense medically directed program. They consumed 500 to 550 calories a day, using a meal replacement called Optifast® (from Nestle) plus vegetables for eight weeks. (It should be noted that fully one-third of them (16) either couldn’t hack it and quit the study or failed to lose the required ten percent of body weight the study required and thus not counted in the results.) But for the 34 participants that did manage to complete the first phase, during the next two weeks, they were gradually reintroduced to ordinary foods in the form of a diet recommended to them by the researchers.
And finally, they were given counseling and written advice about how to maintain their new weight. But it didn’t work. After one year, the participants had regained a substantial portion of the weight they had previously lost.
Specifically, the results were as follows:
- On average, during the first ten weeks, the 34 participants who made it through lost almost 30 pounds — an average of about 3 lbs a week.
- However, their hormone levels of six hormones (most notably leptin and ghrelin) associated with weight management and appetite control changed during the ten weeks in a way that increased their appetites. And in fact, all participants reported feeling hungrier than they did before the study began.
- Leptin is produced in your body’s white fat cells. Not surprisingly, then, the amount of leptin in your bloodstream is proportional to the amount of body fat you have. It acts on the hypothalamus in your brain to control food intake and energy expenditure. When leptin falls, appetite increases and metabolism slows. A year after participants in the study completed the ten week weight loss program, even though their leptin levels were indeed rising as they regained their weight, they were still one-third lower than they were at the start of the study.
- The hormone ghrelin, which is usually considered the counterpart of leptin,7 Klok MD, Jakobsdottir S, Drent ML. “The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review.” Obes Rev. 2007 Jan;8(1):21-34. <http://www.ncbi.nlm.nih.gov/pubmed/17212793> is mainly produced by the P/D1 cells lining the part of the stomach known as the fundus and like leptin, act on the hypothalamus in the brain. Ghrelin stimulates appetite. Thus, the higher the levels in the bloodstream, the greater the desire to eat. Not surprisingly then, ghrelin levels increase before meals and decrease after meals. Notably, ghrelin levels increased during the diet part of the study, and remained higher than normal one year later, thus continuing to induce increased appetite during that entire time period, and beyond.
- After one year, participants had gained back an average of 12 pounds of the weight they had previously lost.
- But the key finding was that levels of the six tracked appetite inducing hormones had not yet returned to pre-study levels, even after one year. Surprisingly, at least to the researchers, the six appetite hormones were still out of whack in a direction that would continue to keep hunger and appetite boosted. Not good for a long term weight management prognosis. As Dr. Rudolph Leibel, an obesity researcher at Columbia, said: while it is no surprise that hormone levels changed shortly after the participants lost weight, “what is impressive is that these changes don’t go away.”
Thus, the conclusion touted in the media that gaining weight back after dieting is not your fault. It’s programmed into your hormones. Or as Dr. Stephen Bloom, an obesity researcher at Hammersmith Hospital in London, said: the study is “showing something I believe in deeply — it is very hard to lose weight.” And, according to Dr. Bloom, the reason is that “your hormones work against you.”
At this point, it’s probably worth talking about Optifast® — what it is and why that matters.
Optifast is a creation of Nestle Nutrition, the people who bring you Boost®. Boost, incidentally is a nutrition drink made from sugar, water, milk protein, vegetable oil, and synthetic vitamins. Optifast builds on that yummy concept to create, what Nestle markets as a “comprehensive [drinks, shakes, soups, bars, and powders], medical weight loss program.” The operative word here is “medical.” Even though the shakes are not much different than Boost, they are notably more expensive and are to be used only with a doctor’s guidance. In other words, they are designed as a money making vehicle for your doctor. No, really! In fact, on their website, Optifast bills its program as a “business partnership” for doctors and clinics.8 “Become an Optifast Provider.” Optifast. (Accessed 6 Nov 2011.) <http://www.optifast.com/Pages/become_a_optifast_provider.aspx> It should also be pointed out that on their site, Optifast states that although the typical patient loses 52 pounds in 22 weeks, for most of those patients, the “weight loss is only temporary”9 Optifast. (Accessed 6 Nov 2011.) <http://www.optifast.com/Pages/optifast_home.aspx> — in line with the study results.
In addition to being designed by the same brilliant minds that brought you Boost’s sugar, synthetic vitamins, unbalanced omega-6 oils, and high allergy dairy proteins,10 “Optifast Weightloss Vanilla Milk Shake Powder.” Drug Dispensary.com. (Accessed 6 Nov 2011). <http://www.drugdispensary.com/products/detail.asp?sku=2093529&bhcp=1> Optifast is expensive, requires working with a physician (which makes it even more expensive), and is based on all liquids plus snack bars (which makes it a difficult program to sustain long term).
But even better, a study just published in the BMJ (nee British Medical Journal) concluded that commercial weight-loss programs such as Weight Watchers and Slimming World are more effective and cheaper than family doctor-based services led by specially trained staff.11 Kate Jolly, Amanda Lewis, Jane Beach, John Denley, Peymane Adab, Jonathan J Deeks, Amanda Daley, Paul Aveyard. “Comparison of range of commercial or primary care led weight reduction programmes with minimal intervention control for weight loss in obesity: Lighten Up randomised controlled trial.” BMJ 2011; 343:d6500. <http://www.bmj.com/content/343/bmj.d6500.full.pdf> Specifically, the study states, “Our findings suggest that a 12 week group based dedicated programme [sic] of weight management can result in clinically useful amounts of weight loss that are sustained at one year in an unselected primary care population with obesity. Interventions provided by primary care showed no evidence of effectiveness. The only programme to achieve statistically significantly greater weight loss than the comparator group was Weight Watchers.” And although this study did not specifically test for Optifast, the results achieved by their doctor-based program were a perfect match for the Optifast plan: initial weight loss that was unsustainable over a year. When it comes to medical weight loss programs supervised by doctors, as they say on the TV show Big Bang Theory, “Bazinga!” When all is said and done, you have to wonder who paid for this study — and whether they were happy with the results.12 <http://www.youtube.com/watch?v=pZi2og1YQJA&feature=results_video&playnext=1&list=
Are the study’s conclusions as cut and dried as presented in the media?
Several experts have pointed out that it was a small study. Only 34 people completed it, and it’s never wise basing broad conclusions on such a small sampling. But that said, it is my guess that those results would hold up were the study to be repeated with larger numbers of participants. My issues with the study do not lie here.
Some people have pointed out that the participants were still at lower weights (an average of 18 lbs lower) than when they started. Yes, but it can logically be assumed that the upward trend will continue since nothing had changed biochemically in the participants bodies, nor in their dietary habits. And, in fact, history tells us that yo-yo dieting is a sad fact of life. So my issues with the study do not lie here either.
Other people have pointed out that while the hormones studied may have a “logical” connection with weight gain, the researchers did not show that the hormones were causing the subjects to gain back their weight. Then again, this result is in line with other studies that have shown the same thing: that dieting changes both your hormonal and your metabolic balance. But if you look at this issue too closely, you will end up missing the forest by focusing too strongly on the trees. Or to put it another way: the analysis that dieting adversely affects hormone levels is correct, but the conclusion that they “control” long-term weight-loss is inaccurate because it is incomplete.
We just discussed the issues brought up by doctors and other obesity researchers. In the end, those concerns were mostly window dressing, brought up to give the appearance of scientific rigor, but ultimately supportive of the study’s conclusions. The problem is: they all were within the proverbial box.
My concerns lie outside the box.
First and foremost, I have a problem with the diet program itself — above and beyond my obvious lack of approval for the Optifast diet foods. The program that the researchers put people on (pretty much the program designed by Nestle for Optifast) violates several key weight loss principles that have been common knowledge to anyone in the field for several decades — at least to those who have not chosen to be willfully ignorant.
Twenty years ago, I wrote, “Caloric restriction diets don’t fail because we cheat; they fail because they are metabolically designed to fail.” I’m not saying I’m brilliant; I’m just saying it’s old knowledge. How is it that the study’s authors did not know it?
When you deprive your body of food, you lose weight rapidly for a few days. But as soon as the body’s built-in “starvation-underdrive” mechanism kicks in, the weight loss begins to slow down…and ultimately stop. What happens is that the body adapts to the caloric restriction, and (in an effort to prevent starvation) “learns” to get by on less energy. Once that happens, it’s almost impossible, no matter how little you eat, to lose any more weight. In fact, you might even find yourself gaining weight on minimal calories.
And later, when you begin to eat normally again, the problem is even worse. For by then, the body has learned to treat any calories beyond the starvation level as excess energy and store them — as fat. In other words, you’ll find yourself gaining weight even faster than before you began your diet. This is the brutally discouraging reason that 95% of all people who lose weight on a low calorie diet regain that weight within a year — again, in line with the study’s results.
The researchers put people on a 500-550 calorie a day program for ten continuous weeks. Based on what has been common knowledge in the weight loss industry for 20 years, as they say in Yiddish, this is mishugina (crazy)! You never want to go extremely low calorie for more than one or two days at a time. Any longer than that and your metabolism begins to reset to starvation mode. The best routine for dieting is one day on, one day off.
But there’s more.
Another problem with the study is that any weight loss program that does not include exercise is doomed to fail for several reasons.
Unless you exercise vigorously every day and make sure that fat comprises less than 20% of your caloric intake (with the exception of certain fats such as extra virgin coconut oil), a lot of your weight loss on a calorie restriction diet will be lean muscle mass — not fat. When this happens, you can find yourself in the unenviable position of being both anorexic and obese at the same time — underweight but with 30% or more of that weight comprised of fat. This has several serious consequences when it comes to weight loss — and particularly when it comes to keeping that weight off.
Muscle burns fat. A pound of muscle burns up to nine times the calories of a pound of fat. In other words, as you build up muscle mass, you increase your resting metabolic rate, which is the number of calories you burn while sleeping or sitting. There is some debate as to how many calories resting muscle actually burns — with estimates ranging from 6-60 calories per day for every pound of new muscle you add to your body (versus 2 calories per pound of fat). In truth, the actual number is probably between 13-25 calories per day. Add ten pounds of muscle, and you’re burning an extra 130-250 calories a day. Now that might not sound like a lot. But contrast that with the people on the Optifast starvation diet who lost 30 lbs without exercising. Without exercise, some 40% of that weight loss could have been muscle. That’s 12 lbs. Now calculate the difference between adding ten lbs of muscle and losing 12, and you’ve got a difference of 22 lbs. So even at the low end, that’s 286 calories a day, or better than a pound every two weeks difference for the year after the diet is over between people who exercise while dieting and those who drop 30 lbs without exercising. How much of a difference in your long term weight outcome do you think two extra pounds a month would make?
In addition, exercise beats genes. Being active can melt away fat — even in those who have inherited DNA that makes them prone to obesity. Researchers at the Medical Research Council’s Epidemiology Unit in Cambridge examined data on genes, weight, and the exercise habits of 220,000 adults from around the world. They found that those with one copy of the FTO obesity gene were 30 percent more likely to be obese than those without it. But in those who exercise, the gene only raised the odds 22 percent. In other words, it cut the effect of the FTO gene by 27 percent. In those with two copies of the gene, it cut the odds of being obese by even more — 42%.13 Kilpeläinen TO, Qi L, Brage S, Sharp SJ, Sonestedt E, et al. 2011 “Physical Activity Attenuates the Influence of FTO Variants on Obesity Risk: A Meta-Analysis of 218,166 Adults and 19,268 Children.” PLoS Med 8(11): e1001116. doi:10.1371/journal.pmed.1001116. <http://www.plosmedicine.org/article/fetchObjectAttachment.action;jsessionid=13CA229AFDB35DCDBD527250EA9DF785.ambra02?uri=info%3Adoi%2F10.1371%2Fjournal.pmed.1001116&representation=PDF>
Brown fat VS white fat
And then there’s brown fat. Brown fat is located around the shoulders, neck, spine, and around major organs and blood vessels. It comprises about five percent of your total fat levels and gets its color from the large number of mitochondria (energy producing organelles) it contains. Brown fat specializes in burning white fat (the fat you want to get rid of) for heat energy. It’s the metabolic activity (or inactivity) of brown fat that makes it easy (or difficult) to lose weight. Back when I first started writing on this topic, just over a quarter of a century ago (my how time flies), I wrote about how scientists had recently discovered Brown Fat Thermogenesis, a metabolic function in which regulator cells (brown fat cells) burn white fat cells to produce heat. Each brown fat cell can burn as much as 20 times its own weight in stored white fat. The trick is that brown fat and white fat have completely different origins. Brown fat is derived from muscle, as confirmed by recent studies.14 Patrick Seale, Bryan Bjork, Wenli Yang, Shingo Kajimura1, Sherry Chin1, Bruce M. Spiegelman, et al. “PRDM16 controls a brown fat/skeletal muscle switch.” Nature 454, 961-967 (21 August 2008). <http://www.nature.com/nature/journal/v454/n7207/full/nature07182.html> Go on a starvation diet with no exercise, and you lose not only muscle, but also brown fat. On the other hand, if you exercise, you increase the amount of muscle and brown fat — improving your ability to burn off calories.
Hormones and exercise
The same hormones that the Optifast study found skewing badly after their ten week diet program are actually improved significantly through exercise. For example:
- Exercise improves your body’s leptin sensitivity. In other words, the more you exercise and build muscle mass, the less leptin it takes to control appetite.15 Dyck DJ. “Leptin sensitivity in skeletal muscle is modulated by diet and exercise.” Exerc Sport Sci Rev. 2005 Oct;33(4):189-94. <http://leptinresearch.org/pdf/cln_leptin_sensitivity_in_skeletal_muscle_is_modulated_by_diet_and_exercise.pdf> On the other hand, if you don’t exercise while dieting, you will lose muscle mass and require ever greater amounts of leptin to control your appetite.
- Both aerobic exercise and weight training cause ghrelin levels to drop, thus helping to suppress appetite. Aerobic exercise has the further benefit of raising peptide YY levels, which further suppresses appetite.16 Broom et al. The influence of resistance and aerobic exercise on hunger, circulating levels of acylated ghrelin and peptide YY in healthy males. AJP Regulatory Integrative and Comparative Physiology, 2008; <http://ajpregu.physiology.org/content/296/1/R29.full>
The bottom line is that even if the hormonal weight loss issues raised by the study were not totally created by the method of weight loss employed by the researchers, they were certainly exacerbated by those protocols.
As I mentioned at the top of the newsletter, the wire services will frequently contact a couple of “outside experts” for their opinions on a study. Unfortunately, this does not involve any questioning or challenging by the reporter — merely finding a supportive expert to fill out the story to give it a little more substance. It’s a long, long way from the days of Woodward and Bernstein digging down into the Watergate break-in to uncover the true story. Let’s take a look at a couple of examples.
One expert cited in several reports on the study is Dr. Rudolph Leibel, the obesity expert at Columbia University in New York mentioned earlier. Dr. Leibel is quoted as saying that losing weight “is not a neutral event,” and that it is no accident that more than 90 percent of people who lose a lot of weight gain it back. “You are putting your body into a circumstance it will resist,” he said. “You are, in a sense, more metabolically normal when you are at a higher body weight.”
Really? The question I would have to ask Dr. Leibel is if a higher body weight is more metabolically normal, then why did this normality only appear in the last couple of decades and only in societies that adopt a Western fast food diet? No one spoke of an obesity epidemic in America 50 years ago, and no spoke of it in the developing world at all until those countries began adopting Western style diets.
Dr. Leibel is also quoted as saying that a dieter’s body rebels against weight loss as an evolutionary holdover from earlier times, when weight loss could threaten survival and reproduction. So, “it’s not surprising at all” that our bodies would fight back for at least a year. “This is probably a more or less permanent response.”
Again, really? So the fact that in “earlier times” our ancestors were far more physically active, hunting and gathering and farming and living life without electricity and machinery and sitting all day long at a desk and in front of a TV doesn’t make a difference. That they ate whole foods and not highly processed, high-fat, high-sugar processed foods like we do today doesn’t matter? And the fact that we now consume an average of 523 more calories per day than we did as recently as 1970 doesn’t matter? At 3,500 calories per pound of body weight, that works out to an extra pound gained per week. And Dr. Leibel doesn’t think that matters — that obesity today is merely an evolutionary holdover?
And then there’s Dr. Jules Hirsch of Rockefeller University, who is also quoted in a number of the study rewrites. According to Dr. Hirsch, “A vast effort to persuade the public to change its habits just hasn’t prevented or cured obesity.” According to Dr. Hirsch, a solution might be to restore hormones to normal levels by giving drugs after dieters lose weight.
Yes more drugs! That’s always a good answer. And this from the people who know weight loss, doctors. After all, Weight Watchers works better than medically supervised programs, and doctors believe Optifast is an effective “business partner” to help their patients lose weight and keep it off.
Look, we’ve been down this road before. How many times have researchers told us that obesity is not our fault and that there’s a medical solution? Think back:
- We don’t have enough bad bacteria in our guts. (Good bacteria, according to the researchers, put weight on whereas bad bacteria keep it off.) And they think they might be able to help us lose weight by transplanting bad bacteria into our guts. As the English are wont to say, “Brilliant!”
- It’s not your fault. It’s the abuse you suffered as a child that’s made you obese. Time spent with a psychotherapist and some appropriate mood enhancing drugs should help.
- It’s not you; it’s your friends. If you hang around with overweight people, you won’t think of yourself as overweight even if you are. It’s valuation by perspective.
- It’s not you; it’s your genes.17 Stephen O’Rahilly and I.Sadaf Farooqi. “Genetics of obesity.”Philos Trans R Soc Lond B Biol Sci. 2006 July 29; 361(1471): 1095–1105. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1642700/>
- And on and on.
Do all of these things affect weight loss? Most likely! But they still play a backbench role compared to the “calories in VS calories out” concept. Yes, they may make it more difficult to lose and maintain proper body weight, but they don’t change the fundamental equation — calories in VS calories out. You need to:
- Eat more nutrient dense foods. A food like broccoli provides more protein per calorie than a lean steak — let alone the new KFC Cheesy Bacon Bowl.18 <http://www.youtube.com/watch?v=zdfO5r8CnGo>
- Avoid dieting for more than two days at a time. You don’t want to slow down your metabolic rate.
- Use smaller plates. A 12 inch dinner plate has 44% more surface area than a ten inch plate. That’s a lot more food and a lot more calories on your plate — without making your plate look that full.
- Take smaller portions. Despite what some people think, eating is not really a competitive sport.19 <http://www.youtube.com/watch?v=_V-2NKUlzns>
- Exercise — aerobic to burn calories and weight training to add muscle. And both to improve your hormonal imbalance and raise your metabolic rate.
- And don’t overdress and don’t set your thermostat too high. Living in a cooler environment will encourage brown fat to burn white fat to keep your core temperature normal. Or to put it another way: making your body work to keep you warm burns calories.
And stop paying attention to media reports on “scientific” studies that don’t intuitively make sense. If they don’t feel right, they probably aren’t.
|↑1||Priya Sumithran, M.B., B.S., Luke A. Prendergast, Ph.D., Elizabeth Delbridge, Ph.D., Katrina Purcell, B.Sc., et al. “Long-Term Persistence of Hormonal Adaptations to Weight Loss.” N Engl J Med 2011; 365:1597-1604October 27, 2011. <http://www.nejm.org/doi/full/10.1056/NEJMoa1105816>|
|↑2||“Not your fault! Hormones linked to weight regain.”Pakistan Observer. November 06, 2011. (Accessed 6 Nov 2011). <http://pakobserver.net/detailnews.asp?id=122315>|
|↑3||Rob Stein. “Hormones make it hard for dieters to stay thin, study indicates.” Washington Post. 25 Oct 2011. (Accessed 5 Nove 2011). <http://www.washingtonpost.com/blogs/the-checkup/post/hormones-make-it-hard-for-dieters-to-stay-thin-study-indicates/2011/10/26/gIQAG9jhJM_blog.html>|
|↑4||Carrie Gann. “Hormones Make It Hard to Keep Weight Off, Study Says.” 27 Oct 2011. ABC News. (Accessed 5 Nov 2011). <http://abcnews.go.com/blogs/health/2011/10/27/hormones-make-it-hard-to-keep-weight-off-study-says/>|
|↑5||“Hunger Hormones Linked to Weight Regain, Study Says.” USA Today. 26 Oct 2011. (Accessed 5 Nov 2011). <http://yourlife.usatoday.com/fitness-food/diet-nutrition/story/2011-10-26/Hunger-hormones-linked-to-weight-regain-study-says/50941242/1>|
|↑6||Associated Press. “Hunger Hormones Linked to Weight Regain, Study Says.” FoxNews.com. 27 Oct 2011. (Accessed 5 Nov 2011). <http://www.foxnews.com/health/2011/10/27/hunger-hormones-linked-to-weight-regain-study-says/>|
|↑7||Klok MD, Jakobsdottir S, Drent ML. “The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review.” Obes Rev. 2007 Jan;8(1):21-34. <http://www.ncbi.nlm.nih.gov/pubmed/17212793>|
|↑8||“Become an Optifast Provider.” Optifast. (Accessed 6 Nov 2011.) <http://www.optifast.com/Pages/become_a_optifast_provider.aspx>|
|↑9||Optifast. (Accessed 6 Nov 2011.) <http://www.optifast.com/Pages/optifast_home.aspx>|
|↑10||“Optifast Weightloss Vanilla Milk Shake Powder.” Drug Dispensary.com. (Accessed 6 Nov 2011). <http://www.drugdispensary.com/products/detail.asp?sku=2093529&bhcp=1>|
|↑11||Kate Jolly, Amanda Lewis, Jane Beach, John Denley, Peymane Adab, Jonathan J Deeks, Amanda Daley, Paul Aveyard. “Comparison of range of commercial or primary care led weight reduction programmes with minimal intervention control for weight loss in obesity: Lighten Up randomised controlled trial.” BMJ 2011; 343:d6500. <http://www.bmj.com/content/343/bmj.d6500.full.pdf>|
|↑13||Kilpeläinen TO, Qi L, Brage S, Sharp SJ, Sonestedt E, et al. 2011 “Physical Activity Attenuates the Influence of FTO Variants on Obesity Risk: A Meta-Analysis of 218,166 Adults and 19,268 Children.” PLoS Med 8(11): e1001116. doi:10.1371/journal.pmed.1001116. <http://www.plosmedicine.org/article/fetchObjectAttachment.action;jsessionid=13CA229AFDB35DCDBD527250EA9DF785.ambra02?uri=info%3Adoi%2F10.1371%2Fjournal.pmed.1001116&representation=PDF>|
|↑14||Patrick Seale, Bryan Bjork, Wenli Yang, Shingo Kajimura1, Sherry Chin1, Bruce M. Spiegelman, et al. “PRDM16 controls a brown fat/skeletal muscle switch.” Nature 454, 961-967 (21 August 2008). <http://www.nature.com/nature/journal/v454/n7207/full/nature07182.html>|
|↑15||Dyck DJ. “Leptin sensitivity in skeletal muscle is modulated by diet and exercise.” Exerc Sport Sci Rev. 2005 Oct;33(4):189-94. <http://leptinresearch.org/pdf/cln_leptin_sensitivity_in_skeletal_muscle_is_modulated_by_diet_and_exercise.pdf>|
|↑16||Broom et al. The influence of resistance and aerobic exercise on hunger, circulating levels of acylated ghrelin and peptide YY in healthy males. AJP Regulatory Integrative and Comparative Physiology, 2008; <http://ajpregu.physiology.org/content/296/1/R29.full>|
|↑17||Stephen O’Rahilly and I.Sadaf Farooqi. “Genetics of obesity.”Philos Trans R Soc Lond B Biol Sci. 2006 July 29; 361(1471): 1095–1105. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1642700/>|