Losing Weight Doesn't Have to Ruin Your Metabolism

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No Unexpected Reduction in Energy Expenditure With Sane Weight Loss.

Plus: 9 Simple Rules Every Dieter Must Follow

In the past weeks I have received a couple of questions which revolved around the notion of diet and exercise induced metabolic shutdown. Although I'd hope that I did answer all your questions more or less to your personal satisfaction, I hope that taking the publication of two very recent papers as an incentive to write a whole article about this complex topic will spare me future lengthy elaborations on what exactly happens, when an obese, overweight or lean person reduces his body weight.

Fast forward to the 9 simple rules if you're in a hurry

Before we are going to take a look at the ahead-of-press publication of a related review in the Journal of the International Society of Sports Nutrition, though, I want to briefly envoke the results a group of researchers from the Christian Albrechts University in Kiel presents in their latest paper in the American Journal of Clinical Nutrition (Pourhassan. 2014).

In the corresponding experiment, Maryam Pourhassan, Anja Bosy-Westphal, Britta Schautz, Wiebke Braun, Claus-C Glüer, and Manfred J Müller investigated the changes in body composition that occur, when overweight individuals lose weight and assessed their impact on resting energy expenditure and insulin resistance. As Pourhassan et al. point out, Little has previously been known about metabolic effects of changes in the composition of either FM or FFM with weight loss and gain." (Pourhassan. 2014)

This is problematic. It should after all be self-evident that the changes in fat mass (FM) and fat free mass (FFM) and their ratio alone will have a significant impact on the resting energy expenditure (REE) of the dieter.

The interaction between "weight loss", energy requirements and health is a very complex issue, one and it's unfortunately still "underinvestigated".

If we also take into consideration that the position of the fat stores, e.g. extremities vs. trunk, will have a major impact on the weight loss related improvements in glucose and lipid metabolism, as well as whole body inflammation, leptin, adiponectin and the production and effects all sorts of other crucially important proteins and hormones, it becomes obvious that the current practice of plugging, body weight, height and age into a formula and hitting the "="-key on your calculator cannot be exactly the ideal solution. And what's more, the fact that the changes in weight and the corresponding metabolic adaptations will recursively influence each other doesn't make the situation simpler, either.

"Metabolic adaptations are a result of changes in body composition and variations in the metabolism of individual body components. Weight loss had a strong effect on improving insulin resistance in overweight and obese individuals (Dengel. 1996; Niskanen. 1996).

What's still missing, though, is the [...] determination of whether metabolic effects of weight loss result from the reduction of specific fat depots (eg, in VAT) or a generalized decline of adipose tissue" (Pourhassan. 2014).

Studies like the one by Dengel et al. (see Figure 1) also provide initial evidence that exercise and diet induced improvements in body composition will have different effects on glucose metabolism, which is unquestionably one of the contemporarily most important health markers (and most common reasons people are unhealthy). Significant improvements of the blood glucose response to an oral glucose tolerance test, for example cannot be achieved solely by exercise. Only a reduction in body fat (and as I would suspect liver and muscle glycogen stores) as it is brought about by negative energy balances will get this job done.

In previous studies, the scientists from the Christian Albrechts University in Kiel have already been able to show that weight loss–related changes in FFM were mainly explained by a reduction in skeletal muscle mass (MM), with a minor contribution of losses of kidney and liver mass. It goes without saying that the latter depends on the original weight of the organ and can be quite pronounced, in obese individuals, with beginning for full-blown NAFLD (Bosy-Westphal. 2013).

This is what the researchers did

In the study at hand, in the course of which 83 healthy subjects - 50% of them obese, the rest normal to overweight - were investigated at 2 occasions with weight changes between -11.2 and +6.5 kg (follow-up periods between 23.5 and 43.5 mo). At both visits to the lab, the scientists measured the...

  • body composition by using the 4-component model and whole-body MRI
  • resting energy expenditure (REE),
  • plasma thyroid hormone concentrations, and
  • insulin resistance

...by standardized methods to elucidate the associations between the changes in body composition, energy expenditure, thyroid hormone levels and glucose metabolism.

Yes, there was no dietary control: In the future it would be nice to see whether or not the means by which the study participants gained and lost weight correlate with the changes in body composition, thyroid hormone levels, resting energy expenditure and insulin sensitivity... the costs for an adequately powered study would yet be exorbitant, I guess.

If we take a look at the amount of muscle the weight losers dropped (-15%) and the -16% reduction in triiodothyronin (T3) and their relation to the accuracy of the calculated vs. measured energy expenditure in Figure 2, it may be surprising to see that the difference between calculated and real energy expenditure of the subjects is comparatively small.

In view of a lean-to-fat mass weight loss ratio of 0.26 and body fat reductions of up to 59.5% (not shown in Figure 2) in the particularly nasty trunk area, it is eventually not that surprising as it may initially seem that the ~11kg the "weight losers" dropped did not result in the often-talked about metabolic shutdown, we see so often in relatively lean individuals whose dream of a cover model physique turns into a nightmare of lifelong dieting.

The data in Figure 3 confirms what the previous remarks implied: It's the lean mass and not the total body mass (right) that determines the resting energy expenditure before and after weight loss (left) and gain (middle). Moreover, a detailed statistical analysis of the date revealed several in- and interdependent associations between the changes in body composition on the one hand, and those of resting energy expenditure, T3 levels and glucose metabolism on the other hand:

"In a first analysis, we included changes in FFM and FM as independent variables. Changes in FM explained 22.8% of the variance in changes in REE(measured), and changes in FFM explained an additional 7.4% of the variance. In a second analysis, we added changes in individual components of FFM (ie, changes in skeletal muscle, bone mass, adipose tissue, heart mass, kidney mass, liver mass, and brain mass) and changes in FM as independent variables. Changes in skeletal muscle explained 29.8% of the variance in changes in REE(measured), and changes in FM explained additional 4.2%."

When changes in plasma triiodothyronine were also included in a third model, an additional increase in the proportion of the explained variance was observed (44.7%). Overall, the changes in skeletal muscle and serum triiodothyronine explained 34.9% and 5.3%, respectively, of the variance in changes in measured REE; and the inclusion of the changes in kidney mass brought about another 4.5% increase of the explanatory value of the scientists' mathematical model.

Significant associations were also observed between HOMA-IR, the classic the marker of insulin resistance, on the one hand, and subcutaneous trunk (r=0.62), and arm and leg fat (r = 0.46). What's quite intriguing, though is that similar correlations for the "bad" visceral fat were observed only in the weight gainers, while "the decrease in SAT of the arms [...]was the only fat depot decrease that was associated with a decrease in the HOMA index with weight loss (r = 0.45, P < 0.012).

Skinny arms and insulin sensitivity? That sounds strange!

It does not only sound strange, it should also remind us of the fact that all the previously discussed correlations are statistics based on a more or less (rather more ;-) uncontrolled investigation into the interactions of weight loss, energy expenditure and metabolic health we should not overestimate.

In fact, this is where paper #2 comes into play. As Eric T Trexler, Abbie E Smith-Ryan, Layne E Norton who focus on in their review of the metabolic adaptation to weight loss on the "implications for athletes point out, there is plenty of good evidence to support the hypothesis that the energy restriction that's necessary for (rapid) weight loss will induce a number of adaptations that serve to prevent further weight loss and conserve energy. Trexler et al. speculate that ...

"[...i]t is likely that the magnitude of these adaptations are proportional to the size of the energy deficit, so it is recommended to utilize the smallest possible deficit that yields appreciable weight loss." (Trexler. 2014)

Consequently, they recommend (just like I did in previous articles) to adopt moderate energy deficits (my suggestion: 20-30% of the habitual, not the calculated energy intake), knowing that it will not just decrease the rate of weight loss, but also minimize the unfavorable adaptations that challenge successful reduction of fat mass. In conjunction with a high(er) protein intake of >25% of the total energy intake and (my suggestion) at least 30g of high EAA protein with every meal (e.g. dairy, eggs, fish, pork, beef, chicken, turkey, and pea-protein for the vegans) this will facilitate stepwise body fat reductions with minimal reductions in lean body mass and a bearable impact on athletic performance.

There is no "magic macronutrient ratio": Although I do believe that many of you have finally realized that there is no magic weight loss pill, the emails and messages I receive on a daily basis leave no doubt that even SuppVersity readers have been bamboozled by the "magic macro numbers" that are thrown around all over the Internet. If there is a number you should you should remember, it's "30" as in 30g of quality protein with every meal" (make it 20g for "snacks" and read my interview w/ Sean Casey for more information on this issue).

It is moreover imperative that you keep lifting heavy objects while you're dieting. As I have outlined in my article "Protein Intake & Muscle Catabolism: Fasting Gnaws on Your Muscle Tissue and Abundance Causes Wastefulness" (read it) the increase in dietary protein will keep the protein synthesis elevated. What it won't do, however is to battle the diet induced expression of catabolic muscle proteins (read more) and the inevitable drop in testosterone and IGF-1, I wrote about only recently in my article "High Protein Diets Don't Counter Anti-Anabolic Effects of Low Energy Intake" (learn more about the hormonal sides of dieting).

Take home message for the physique oriented dieter

The following list of rules, which is based on the latest bro- and pro-scientific evidence is going to help you make the most of your next diet,

  • stick to stepwise reductions of total energy intake - start with 15% and increase in 5-10% steps, whenever you hit a plateau
  • if not absolutely necessary limit your energy deficit to max. 40% - if you hit a plateau, take two weeks off and begin dieting again, instead of running yourself into the ground
  • keep lifting heavy while you're dieting to minimize muscle loss - you can use bot inter- (e.g. 1x powerlifting, 2x higher rep bodybuilding or circuit training routines per week) as well as intra-workout periodization (eg. a heavy compound lift for 5x5 and auxiliary exercises for 3x10 reps and 4x15 reps)
  • use your diet, and only your diet to generate an energy deficit - there is room for both high intensity interval and classic low intensity steady state (walking on an inclined treadmill) exercise, but it must not be done to "burn calories" (learn why) - unless, obviously, you actually want to feel miserable and accelerate the fal loss stalling adaptive reduction in energy expenditure
  • increase in protein intake to >25% of total energy - as long as you stick to the "-40% max"-rule this should leave enough room for the "magic" 2x RDA (1.6g/kg) value of which a study by Pasiakos showed that it produces a better lean-to-fat mass loss ratio than a diet with 2.4g/kg protein (learn more)
  • consume at least 30g of EAA-rich protein per meal - this will bring you up to the magic 10g of EAAs which have been shown to be associated with improved body composition in epidemiological studies (don't use isolated amino acids, instead - they are non-satiating and have inferior metabolic and protein anabolic effects)
  • implement regular refeeds, whenever your total energy deficit is >25% - the refeeds will consist of a single day of 10-15% above maintenance energy intake with a focus on carbohydrates, and should be implemented once or twice a week; they are are believed "to temporarily increase circulating leptin and stimulate the metabolic rate" (Trexler. 2014) and will thus postpone the occurrence of weight loss plateaus
  • fill yourself up with vegetables - except from a few "high energy" exceptions you can and should eat as many veggies as possible; aside from the tons of healthy vitamins and phytonutrients, the mere increase in food volume is going to have a major metabolic impact that goes way beyond an increase in satiety and cannot be achieved with powdered and is significantly reduced with juiced vegetables (you can still "juice", if you insist even waste money on greens supplements, but their benefits will never be up to fresh produce)
  • avoid post-starvation obesity by working your way up to your habitual energy intake progressively - this is particularly important to avoid the formation of new fat cells (=adipocyte hyperplasia), which are currently believed to stick "forever" (=the cells whole life-cycle of ~10 years); neither the pizza and McDonald's diet, nor - and this is something most people tend to overlook - returning to the dietary habits that brought you into a situation, where dietary restriction became obligatory to get (back) in shape are feasible ways of eating after a diet; increase your energy intake in <5% steps every three days and watch the scale and your image in the mirror carefully to minimize fat gains (it's impossible not to gain a minimal amount of fat)


While all of these recommendations have anecdotal evidence (many of them from generations of fighters, bodybuilders and figure athletes), not all are "scientifically proven" - the procedure of reverse dieting, for example, sounds logical, it appears to work, but a study that would compare the changes in body composition on a slow "on-ramp" to those which occur, when you return to a whole-foods, junk-food free maintenance diet - ie. the litmus test for reverse dieting - has yet to be conducted.

Bottom line: In spite of the fact that the primary sources (Pourhassan. 2014 & Trexler. 2014) today's SuppVersity article is based on deal with totally different subject populations, i.e. obese sedentary vs. lean and athletic, the rules I formulated towards the end of the article can be used to optimize and sustain fat (not just weight) loss by all dieters from the Biggest Loser candidate, whose life depends on a 50% reduction to the (almost) shredded physique athlete who does not want to sacrifice his / her health and future physique for the one triumph that may bring him / her a pro-card in whatever division he or she may be competing in.


  • Bosy-Westphal, A., et al. "Effect of weight loss and regain on adipose tissue distribution, composition of lean mass and resting energy expenditure in young overweight and obese adults." International Journal of Obesity 37.10 (2013): 1371-1377.

  • de Graaf, Cees. "Why liquid energy results in overconsumption." Proceedings of the Nutrition Society 70.02 (2011): 162-170.

  • Dengel, Donalald R., et al. "Distinct effects of aerobic exercise training and weight loss on glucose homeostasis in obese sedentary men." Journal of Applied Physiology 81.1 (1996): 318-325.

  • Niskanen, L., et al. "The effects of weight loss on insulin sensitivity, skeletal muscle composition and capillary density in obese non-diabetic subjects." International journal of obesity and related metabolic disorders: journal of the International Association for the Study of Obesity 20.2 (1996): 154-160.

  • Pourhassan, Maryam, et al. "Impact of body composition during weight change on resting energy expenditure and homeostasis model assessment index in overweight nonsmoking adults." The American journal of clinical nutrition (2014): ajcn-071829.

  • Rolls, Barbara J., and Liane S. Roe. "Effect of the volume of liquid food infused intragastrically on satiety in women." Physiology & behavior 76.4 (2002): 623-631.

  • Trexler et al. Metabolic adaptation to weight loss: implications for the athlete." Journal of the International Society of Sports Nutrition 11 (2014):7.