Train Loco Readers…How Are We Doing This Month!? Today we have a great and informative guest article by our friend and colleague, Eric Trexler. Eric is currently a graduate student and researcher at the University of North Carolina (Go Tar Heels basketball!). We asked Eric to write a guest post for our site because we had some great talks with him at the ISSN and NSCA Conferences these past months, as well as via email on Metabolic Adaptation. This is a fascinating area that all three of us have a strong interest in, so we figured what better than to have a real researcher, strength coach, and natural bodybuilder/powerlifter do a guest post on the harsh realities of weight loss. Without further ado, please give your undivided attention to Eric Trexler. Enjoy!
-Eric and Chris
There are innumerable reasons to lose weight. Whether you’re aiming to improve your health or appearance, make a lower weight-class, or get yourself a pro card in bodybuilding, weight loss is a common goal shared by many.
A few months ago, I published an article in the Journal of the International Society of Sports Nutrition (18).This paper reviewed the literature pertaining to metabolic consequences of dieting, with an emphasis on athletic populations. At first glance, the paper might be perceived as somewhat pessimistic, as it acknowledges that the metabolic adaptations to dieting make it a bit of an uphill battle. I prefer to view it differently— if we can identify and acknowledge the difficulties and hurdles faced by dieters, we can then identify solutions. But in order to circumvent these obstacles, we have to acknowledge 4 unfortunate realities of weight loss.
1. Your Metabolism Will Adapt
Our body’s cells require energy to maintain life. As you can imagine, our bodies take the job of maintaining an adequate ATP supply very seriously.
When you diet, you lose body mass. Naturally, you would expect that less overall tissue equals less demand for energy, and therefore a reduction in metabolic rate. This is absolutely true, but with weight loss, the issue goes a bit deeper— metabolic rate often slows down beyond the amount we would expect from decreased body mass (4, 15).
In my publication in JISSN, I review this topic in detail. In short, a number of adaptations contribute to this reduction in energy expenditure (metabolic rate).
We see reductions in hormones related to metabolic rate, including thyroid hormone and leptin. Further, the reduction in anabolic hormones and increase in catabolic hormones threaten the retention of lean mass, which has a particularly high metabolic demand. We also see increased efficiency of energy production— proton leak (1) and the expression of uncoupling proteins (6) may be reduced. To fuel the energy-consuming processes in our bodies, we must convert energy from stored or ingested substrates (i.e. carbs, fats, proteins) to ATP. Normally, this conversion is about 35-40% efficient, meaning that 60-65% of the energy generated in this process is “lost” as heat. When efficiency increases, we lose less of this energy in the conversion process. This means we can meet our demand for ATP by burning less calories, which serves to reduce metabolic rate and oppose our weight loss goals.
The numerous metabolic adaptations to calorie restriction and weight loss result in a clear response: reduced metabolic rate. This affects total daily energy expenditure, basal metabolic rate, calories burned during exercise activity, calories burned during non-exercise activity, and the overall thermic effect of feeding (12).
As you can see, the human body appears to fight perceived starvation by increasing its efficiency. When you impose an “energy crisis” by dieting, these adaptations serve to reduce energy expenditure. It’s the metabolic equivalent of cutting coupons or tightening up your budget during tough economic times.
2. You Will Lose Lean Body Mass
To be fair, this one doesn’t necessarily apply to everybody. If you’re dieting from 30% body fat to 25%, you can probably do so with minimal loss of lean mass. In addition, if you have been under-eating protein or had not been lifting, you could even gain lean mass while losing fat by increasing protein consumption and starting a properly-designed resistance training program.
But if you’re shooting for a stage-ready, competition-level body fat, the loss of lean mass is pretty much inevitable. In the past two years, two different case studies have documented contest preparation in male natural bodybuilders (9, 16). Although both competitors were on well-designed diet and training programs, they lost 6.2 (16) and 14.0 (9) pounds of lean mass, respectively.
Realistically, a natural athlete will not likely approach 5-6% body fat without a loss of lean mass. But in all honesty, the case studies previously mentioned could be considered quite encouraging. One athlete lost 14.0 lbs of lean mass, but 36.9 lbs overall, meaning they lost 22.9 lbs of fat. The other athlete lost only 6.2 lbs of lean mass while losing 30.8 lbs overall— nearly 80% of the total weight lost was fat! So while we must accept that natural athletes tend to lose some lean mass while dieting, we can certainly strive to push the proportion of fat loss up.
3. You Will Get Hungry
Insulin and leptin are both considered “anorexigenic” hormones. Put simply, these hormones relay the message that there is plenty of energy available, leading to increased satiety and decreased hunger. Conversely, ghrelin is considered an orexigenic hormone; ghrelin rises just prior to meals, and it functions to stimulate hunger and food intake.
Leptin is released from fat cells, and smaller fat cells are more sensitive to insulin (12). In the context of a weight loss diet, fat cells shrink in size. Accordingly, studies have shown that weight loss diets result in decreased leptin and insulin, along with increased ghrelin (18). On top of these endocrine effects, there are a number of adaptations within the brain, along with psychological factors of dieting, that increase the desire to eat (12).
Sure, there are some hard gainers out there that are so sick of force-feeding that they welcome the idea of decreased food intake. But for the overwhelming majority of dieters, hunger is an unavoidable reality, especially as body fat gets truly low.
4. Weight Maintenance is Challenging
Let’s say you weigh 190 lbs. If you can drop to 171 lbs and maintain that weight for one year, you are fairly exceptional— less than 20% of individuals are able to lose 10% of their bodyweight and maintain that weight loss for one year (10).
In reality, weight loss is not the hard part. Countless studies have successfully induced weight loss with all kinds of diet and exercise programs. But when you shift your focus from the 10-week studies to those lasting 6 months, 12 months, or beyond, you start to see that maintaining weight loss is a much more difficult task.
We previously discussed that metabolic rate is generally reduced in response to weight loss and reduced caloric intake. Unfortunately, many of the underlying adaptations persist after active weight loss is achieved and weight maintenance is underway. This means that even though you think you’re “done” losing weight, we still see a repressed metabolic rate, altered hormone concentrations, and increased hunger and desire to eat. While some of these adaptations may subside after prolonged, successful weight maintenance, evidence has suggested that some may persist for over a year after weight loss (11, 14).
The presence of these adaptations set the dieter up for a phenomenon known as post-starvation obesity, or body fat overshooting (5, 19). When the diet is “over,” the individual is left with a repressed metabolic rate, and an overwhelming desire to eat. This combination can result in huge, compensatory caloric intakes that lead to rapid fat gain. There is also evidence that weight is preferentially gained as fat mass in this post-diet period (19), and we are particularly susceptible to adipocyte hyperplasia (the addition of entirely new fat cells) (8). These factors may lead to body fat overshooting, where the dieter actually ends up with more fat mass than they had before the diet. In support of this idea, previous research has shown that in athletes engaged in weight-class sports, the number of times they made weight correlates with obesity later in life (17). This means that along with completely nullifying the previous weight loss, this may make it more difficult to get lean in the future.
The Bright Side
By now, I’ve probably convinced you that weight loss is a futile endeavor, and that you’re doomed to fail. But remember to look at the bright side: if we identify the challenges, we can find solutions. We know that your metabolism will adapt, you’ll lose some lean mass, you’ll get hungry, and maintaining your weight loss will be hard. But by employing some effective strategies, you may be able to attenuate some of these challenges.
First, the basics: You need to eat enough protein, and you need to engage in a well-structured resistance training program. Protein is highly satiating and has the highest thermic effect of any macronutrient (13). Sufficient protein intake, combined with effective resistance training (2), also helps prevent the loss of lean mass and the subsequent reduction in energy expenditure.
You also need to allow yourself plenty of time to diet. Adaptations to weight loss are likely proportional to the size of the caloric deficit, and rapid weight loss is associated with greater loss of lean mass (3). So, start your diet with the smallest possible deficit that allows appreciable weight loss— or as my colleague/co-author Layne Norton would say, “Diet on as many calories as you possibly can” (paraphrased). As weight loss begins to plateau, make conservative adjustments to your diet or exercise program, and continue this process in a slow, stepwise manner. Also, while cardio is a useful tool for weight loss, be sure to use it conservatively as well. High volumes of cardio may interfere with recovery from resistance exercise, and you’ll want to avoid the interference effect of concurrent training as much as possible (20). For more information on effective weight loss and contest preparation strategies, refer to the excellent review paper by Helms et al. (7).
In the world of natural bodybuilding, carbohydrate refeeds are very common. This typically refers to one or two days per week in which caloric intake is increased, with a large increase in carb intake. Theoretically, this strategy may influence hunger and metabolic rate by temporarily increasing leptin (18). More research is needed to determine if this strategy makes a significant impact in the context of weight loss.
Another common practice is called “reverse dieting.” This strategy is aimed at avoiding rapid fat gain after the diet (post-starvation obesity, or body fat overshooting). In the immediate post-diet time period, the body is particularly susceptible to fat gain. So, instead of transitioning straight to a huge caloric surplus, reverse dieting refers to gradually increasing caloric intake. In theory, this could assist in gradually reversing adaptations to weight loss and recovering lean mass, while minimizing fat regain (18). Obviously it is unrealistic to maintain true contest shape year-round, but gradual reintroduction of calories may attenuate the rapid fat gain and body fat overshooting that could make future contest preps even more difficult. Again, more research is needed to evaluate the effectiveness of a controlled reverse diet.
Weight loss and weight maintenance are no walk in the park, but you probably figured that out by the alarming prevalence of obesity, and the small number of bodybuilders achieving truly exceptional conditioning. When losing weight, you’ll run into some obstacles that make the process a bit challenging. However, by employing some effective training and nutrition strategies, you can attenuate these challenges and set yourself up for success.
IF YOU WOULD LIKE TO LEARN MORE ABOUT OUR SERVICES AND HOW WE CAN DESIGN YOU A INDIVIDUALIZED FLEXIBLE DIETING NUTRITION PROGRAM AROUND YOUR GOALS, SCHEDULE, PREFERENCES, ETC. PLEASE VISIT US HERE OR CONTACT US HERE FOR A FREE PHONE CONSULTATION.
About the author:
Eric Trexler is a strength coach, powerlifter, and natural bodybuilder, and serves as the Director of Research and Education for INOV8 Elite Performance. He is also a graduate student and active researcher, conducting exercise and nutrition research at the University of North Carolina at Chapel Hill.
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