Diet versus exercise in “the biggest loser” weight loss competition

Background:

Obesity experts have criticized The Biggest Loser television show for its portrayal of an unrealistic intervention that raises false expectations for weight loss. However, the magnitude of the diet and exercise intervention has not been previously quantified.

Design and Methods:

Using a validated computational model of metabolism, I quantified the diet and exercise intervention by integrating data on energy expenditure, body weight and fat mass collected during The Biggest Loser competition.

Results:

Participant body mass index, weight, and percent body fat at baseline were 48.7 ± 10.1 kg/m², 144.9 ± 39.4 kg, and 49 ± 6% (mean ± SD), respectively. During the first phase of the competition when the contestants were isolated in a boot camp environment, the average rate of weight loss was 0.4 ± 0.1 kg/d and decreased to 0.19 ± 0.1 kg/d after returning home. Total weight loss was 58.2 ± 26 kg with 81.6 ± 8.4% coming from body fat. The computer simulations closely matched these data and calculated that average energy intake decreased by 65% during the first phase to 1300 kcal/d while participating in 3.1 h/d of vigorous exercise. After returning home, energy intake increased to 1900 kcal/d and vigorous exercise decreased to 1.1 h/d. Simulation of diet alone resulted in 34 kg of weight loss with 65% coming from body fat, whereas exercise alone resulted in a loss of 27 kg with 102% from fat.

Conclusion:

The intense diet and exercise intervention during The Biggest Loser competition were not sustainable. However, a relatively modest permanent lifestyle intervention of 20% caloric restriction and 20 min/d of vigorous exercise could maintain the massive weight loss.     

The effects of reality television on weight bias: an examination of The Biggest Loser

Weight-loss reality shows, a popular form of television programming, portray obese individuals and their struggles to lose weight. While the media is believed to reinforce obesity stereotypes and contribute to weight stigma, it is not yet known whether weight-loss reality shows have any effect on weight bias. The goal of this investigation was to examine how exposure to 40-min of The Biggest Loser impacted participants' levels of weight bias. Fifty-nine participants (majority of whom were white females) were randomly assigned to either an experimental (one episode of The Biggest Loser) or control (one episode of a nature reality show) condition. Levels of weight bias were measured by the Implicit Associations Test (IAT), the Obese Person Trait Survey (OPTS), and the Anti-fat Attitudes scale (AFA) at baseline and following the episode viewing (1 week later). Participants in The Biggest Loser condition had significantly higher levels of dislike of overweight individuals and more strongly believed that weight is controllable after the exposure. No significant condition effects were found for implicit bias or traits associated with obese persons. Exploratory analyses examining moderation of the condition effect by BMI and intention to lose weight indicated that participants who had lower BMIs and were not trying to lose weight had significantly higher levels of dislike of overweight individuals following exposure to The Biggest Loser compared to similar participants in the control condition. These results indicate that anti-fat attitudes increase after brief exposure to weight-loss reality television.     

The Obesity Epidemic: A Consequence of Reduced Energy Expenditure and the Uncoupling of Energy Intake?

Obesity prevalence has increased, and increased energy intake or decreased physical activity are the two most obvious contributing factors. The percentage of Americans engaging in exercise has been stable over the past few decades, but decreases in occupation‐related energy expenditure are sufficient to partially explain increased obesity prevalence. Further, the contribution of energy intake and energy expenditure to the obesity epidemic is complicated because they are not independent—they are influenced by each other. For example, Mayer found that low activity levels were marked by higher body weight and higher “unregulated” energy intake levels. Conversely, higher activity levels were marked by lower body weight and energy intake that matched energy expenditure. Consistent with Mayer, we propose that because most Americans have low levels of occupation‐related activity, they do not benefit from the regulation of energy intake achieved at higher activity levels, resulting in weight gain due to energy intake exceeding energy expenditure.     

Petite bodies of the “robust” australopithecines

The “robust” australopithecines are often depicted as having large and powerfully built bodies to match their massive masticatory apparatus, but until 1988 the sample of postcranial remains attributed with certainty to this group was very limited. Almost nothing was known about the body of the East African “robust” australopithecine because taxonomic attribution of the postcrania was so uncertain. The body of the South African “robust” australopithecine had to be reconstructed from about a dozen isolated fragments of postcrania. Now a partial skeleton is attributed with confidence to the East African “robust” group along with several isolated bones. The South African sample has more than tripled. Analyses of this vastly expanded sample reveal that a large portion of postcrania attributed to “robust” australopithecines from Swartkrans Member 1 (35%) are from extraordinarily small-bodied individuals similar in size to a modern Pygmy weighing as little as 28 kg. These small elements include parts from the forelimb, spine, and hindlimb. About 22% of these Swartkrans 1 “robust” australopithecines are about the same size as a modern human weighing about 43 kgs and about 43% are larger than this standard but less than or equal to a 54 kg modern human. Approximately the same pattern is true for the Swartkrans 2 hominids, but taxonomic attribution is less certain. All of the Member 3 specimens are similar in size to the 45 kg standard. The partial skeleton of the East African “robust” australopithecine (KNM-ER 1500) has hindlimb joints that would correspond to a modern human of 34 kgs although the actual weight may be 5 to 10 kgs greater judging from shaft robusticity and forelimb size. The largest postcranial element attributed with some certainty to the East African “robust” australopithecine group (the talus, KNM-ER 1464) is about the same overall size as a modern human of 54 kgs, although its tibial facet is slightly smaller. Although many previous studies have hinted at the possibility that “robust” australopithecines had relatively small bodies, the new fossils provide substantial evidence that these creatures ranged from quite small to only moderate in body size relative to modern humans. These were the petite-bodied vegetarian cousins of our ancestors. Sexual dimorphism in body size appears to be greater than that in modern humans, similar to that in Pan, and less than that in Gorilla or Pongo, although such comparisons are of limited value given the small samples, poorly known body proportions, time averaging, and many other problems.     

Metabolic Determinants of Weight Gain in Humans

One of the fundamental challenges in obesity research is to identify subjects prone to weight gain so that obesity and its comorbidities can be promptly prevented or treated. The principles of thermodynamics as applied to human body energetics demonstrate that susceptibility to weight gain varies among individuals as a result of interindividual differences in energy expenditure and energy intake, two factors that counterbalance one another and determine daily energy balance and, ultimately, body weight change. This review focuses on the variability among individuals in human metabolism that determines weight change. Conflicting results have been reported about the role of interindividual differences in energy metabolism during energy balance in relation to future weight change. However, recent studies have shown that metabolic responses to acute, short‐term dietary interventions that create energy imbalance, such as low‐protein overfeeding or fasting for 24 hours, may reveal the underlying metabolic phenotype that determines the degree of resistance to diet‐induced weight loss or the propensity to spontaneous weight gain over time. Metabolically “thrifty” individuals, characterized by a predilection for saving energy in settings of undernutrition and dietary protein restriction, display a minimal increase in plasma fibroblast growth factor 21 concentrations in response to a low‐protein overfeeding diet and tend to gain more weight over time compared with metabolically “spendthrift” individuals. Similarly, interindividual variability in the causal relationship between energy expenditure and energy intake (“energy sensing”) and in the metabolic response to cold exposure (e.g., brown adipose tissue activation) seems, to some extent, to be indicative of individual propensity to weight gain. Thus, an increased understanding and the clinical characterization of phenotypic differences in energy metabolism among individuals (metabolic profile) may lead to new strategies to prevent weight gain or improve weight‐loss interventions by targeted therapies on the basis of metabolic phenotype and susceptibility to obesity in individual persons.     

The crown joules: energetics,ecology, and evolution in humans and other primates

Biological diversity is metabolic diversity: Differences in anatomy, physiology, life history, and activity reflect differences in energy allocation and expenditure among traits and tasks. Traditional frameworks in primatology, human ecology, public health, and paleoanthropology view daily energy expenditure as being more variable within than between species, changing with activity level but essentially fixed for a given body size. Growing evidence turns this view on its head. Total energy expenditure (kcal/d), varies relatively little within species, despite variation in physical activity; it varies considerably among species even after controlling for the effect of body size. Embracing this emerging paradigm requires rethinking potential trade‐offs in energy allocation within and between species, assessing evidence of metabolic acceleration within lineages, and abandoning activity‐based estimates of total energy expenditure. Difficult and exciting work lies ahead in the effort to untangle the ecological and evolutionary pressures shaping primate metabolic diversity.     

Physical activity and body functionality: implications for obesity prevention and treatment

Physical activity promotes metabolic adaptations that improve body functionality and contribute to the prevention of some diseases. With respect to energy and fat balance, physical activity facilitates the equilibrium between energy intake and expenditure as well as between fat intake and fat oxidation. When combined with a healthy diet that favors satiety with a reduced energy intake, exercise can induce a substantial mass loss in obese individuals. However, even the impact of an exemplary lifestyle does not seem to have the potential to decrease body mass in obese individuals down to the mass range of lean people. Up to now, we have not been able to induce mass changes exceeding 12%-15% initial body mass in obese male subjects under tolerable exercise and dietary habits, and this moderate success was accompanied by modifications in appetite and energy expenditure susceptible to compromise subsequent mass stability. As described in this paper, many environmental factors can influence energy balance and the ability to lose body fat in response to a healthy diet and (or) physical activity program. Particular attention is given to preliminary data obtained in our laboratory that suggest that knowledge-based work does not favor the same potential mass reducing effects as physical work. In fact, the acute effects of knowledge-based work suggest that this work modality may be rather susceptible to promote a more pronounced positive energy balance compared with what we may expect from a sedentary relaxing activity. This is problematic for obesity prevention in the future since knowledge-based work now represents the main working modality in a context of modernity.     

Increase of efficiency of adaptations and attenuation of organism protective reactions in the process of biological evolution

The major trend in evolution of living organisms is development of the central nervous system and sense organs, an increase of energy exchange, development of homoiothermy and of increasingly more complex forms of behavior, an increase in energy expenditure in connection with a rise of body activity and with development of adaptation to habitat. Such fundamental processes of evolution were and still have been subjected to numerous investigations and discussions. However, in different animals there exist different species-specific peculiarities of evolution of physiological functions, from which eventually the fundamental evolutionary processes are formed. We studied some of these specific processes by separating them into two categories. The first category is “Rise in efficiency of adaptations” in development of biological evolution. By this term we mean development of the amazingly perfect specific physiological mechanisms of adaptive character. The second category is “Weakening of the protective body reactions” under which we mean disturbances of the protective mechanisms of the body immune system, uncoordinated leukocyte movement in microvessels, lack of effective collateral blood circulation in brain and heart, etc.     

Comparative primate energetics and hominid evolution

There is currently great interest in developing ecological models for investigating human evolution. Yet little attention has been given to energetics, one of the cornerstones of modern ecosystem ecology. This paper examines the ecological correlates of variation in metabolic requirements among extant primate species, and uses this information to draw inferences about the changes in energy demands over the course of human evolution. Data on body size, resting metabolism, and activity budgets for selected anthropoid species and human hunter-gatherers are used to estimate total energy expenditure (TEE). Analyses indicate that relative energy expenditure levels and day ranges are positively correlated with diet quality; that is, more active species tend to consume more energy-rich diets. Human foragers fall at the positive extremes for modern primates in having high expenditure levels, large ranges, and very high quality diets. During hominid evolution, it appears that TEE increased substantially with the emergence of Homo erectus. This increase is partly attributable to larger body size as well as likely increases in day range and activity level. Assuming similar activity budgets for all early hominid species, estimated TEE for H. erectus is 40–45% greater than for the australopithecines. If, however, it is assumed that the evolution of early Homo was also associated with a shift to a more “human-like” foraging strategy, estimated expenditure levels for H. erectus are 80–85% greater than in the australopithecines. Changing patterns of resource distribution associated with the expansion of African savannas between 2.5 and 1.5 mya may been the impetus for a shift in foraging behavior among early members of the genus Homo. Such ecological changes likely would have made animal foods a more attractive resource. Moreover, greater use of animal foods and the resulting higher quality diet would have been important for supporting the larger day ranges and greater energy requirements that appear to have been associated with the evolution of a human-like hunting and gathering strategy. Am J Phys Anthropol 102:265–281, 1997 © 1997 Wiley-Liss, Inc.     

Prolonged fasting induces long-lasting metabolic consequences in mice

To endure prolonged fasting, animals undergo important acute physiological adjustments. However, whether severe fasting also leads to long-term metabolic adaptations is largely unknown. Forty-eight-hour fasting caused a pronounced weight loss in adult C57BL/6 male mice. Seven days of refeeding increased body adiposity to levels above baseline, whereas fasting-induced reductions in lean body mass and energy expenditure were not fully recovered. Respiratory exchange ratio and locomotor activity also remained altered. A fasting/refeeding cycle led to persistent suppression of Pomc mRNA levels and significant changes in the expression of histone deacetylases and DNA methyltransferases in the hypothalamus. Additionally, histone acetylation in the ventromedial nucleus of the hypothalamus was reduced by prolonged fasting and remained suppressed after refeeding. Mice subjected to 48-h fasting 30 days earlier exhibited higher body weight and fat mass compared to aged-matched animals that were never food-deprived. Furthermore, a previous fasting experience altered the changes in body weight, lean mass, energy expenditure and locomotor activity induced by a second cycle of fasting and refeeding. Notably, when acutely exposed to high-palatable/high-fat diet, mice that went through cumulative fasting episodes presented higher calorie intake and reduced energy expenditure and fat oxidation, compared to mice that had never been subjected to fasting. When chronically exposed to high-fat diet, mice that experienced cumulative fasting episodes showed higher gain of body and fat mass and reduced energy expenditure and calorie intake. In summary, cumulative episodes of prolonged fasting lead to hypothalamic epigenetic changes and long-lasting metabolic adaptations in mice.     

Resistance training increases total energy expenditure and free-living physical activity in older adults.

The purpose of this study was to determine what effects 26 wk of resistance training have on resting energy expenditure (REE), total free-living energy expenditure (TEE), activity-related energy expenditure (AEE), engagement in free-living physical activity as measured by the activity-related time equivalent (ARTE) index, and respiratory exchange ratio (RER) in 61- to 77-yr-old men (n = 8) and women (n = 7). Before and after training, body composition (four-compartment model), strength, REE, TEE (doubly labeled water), AEE (TEE - REE + thermic response to meals), and ARTE (AEE adjusted for energy cost of standard activities) were evaluated. Strength (36%) and fat-free mass (2 kg) significantly increased, but body weight did not change. REE increased 6.8%, whereas resting RER decreased from 0.86 to 0.83. TEE (12%) and ARTE (38%) increased significantly, and AEE (30%) approached significance (P = 0.06). The TEE increase remained significant even after adjustment for the energy expenditure of the resistance training. In response to resistance training, TEE increased and RER decreased. The increase in TEE occurred as a result of increases in both REE and physical activity. These results suggest that resistance training may have value in increasing energy expenditure and lipid oxidation rates in older adults, thereby improving their metabolic profiles.     

Energy metabolism and the evolution of reproductive suppression in the human female

Reproduction places severe demands on the energy metabolism in human females. When physical work entails higher energy expenditure, not enough energy will be left for the support of the reproductive processes and temporal suppression of the reproductive function is expected. While energy needed for reproduction may be obtained by increases in energy intake, utilization of fat reserves, or reallocation of energy from basal metabolism, several environmental or physiological constraints render such solutions unlikely. For human ancestors increases in energy intake were limited by availability of food, by labor of food preparation and by metabolic ceilings to energy assimilation. Energy stored as fat may support only a fraction of the requirements for reproduction (especially lactation). Effects of intense physical activity on basal metabolism may also interfere with fat accumulation during pregnancy. Finally, the female physiology may experience demands on increasing the basal metabolism as a consequence of physical activity and, at the same time, on decreasing the basal metabolism, when energy to support the ongoing pregnancy or lactation is inadequate. The resulting metabolic dilemmas could constitute a plausible cause for the occurrence of reproductive suppression in response to physical activity. It is, therefore, likely that allocating enough energy to the reproductive processes during periods when energy expenditure rises may be difficult due to physiological and bioenergetic constraints. Females attempting pregnancy in such conditions may compromise their lifetime reproductive output. A reproductive suppression occurring in low energy availability situations may thus represent an adaptive rather then a pathological response.     

Inactivation of PKCtheta leads to increased susceptibility to obesity and dietary insulin resistance in mice

In this study, we investigated the metabolic phenotype of PKCtheta knockout mice (C57BL/6J) on chow diet and high-fat diet (HFD). The knockout (KO) mice are normal in growth and reproduction. On the chow diet, body weight and food intake were not changed in the KO mice; however, body fat content was increased with a corresponding decrease in body lean mass. Energy expenditure and spontaneous physical activity were decreased in the KO mice. On HFD, energy expenditure and physical activity remained low in the KO mice. The body weight and fat content were increased rapidly in the KO mice. At 8 wk on HFD, severe insulin resistance was detected in the KO mice with hyperinsulinemic euglycemic clamp and insulin tolerance test. Insulin action in both hepatic and peripheral tissues was reduced in the KO mice. Plamsa free fatty acid was increased, and expression of adiponectin in the adipose tissue was decreased, in the KO mice on HFD. This study suggests that loss of PKCtheta reduces energy expenditure and increases the risk of dietary obesity and insulin resistance in mice.     

Body weight prediction in early fossil hominids: Towards a taxon-“independent” approach

The choice of a model taxon is crucial when investigating fossil hominids that clearly do not resemble any extant species (such as Australopithecus) or show significant differences from modern human proportions (such as Homo habilis OH 62). An “interhominoid” combination is not adequate either, as scaling with body weight is strongly divergent in African apes and humans for most skeletal predictors investigated here. Therefore, in relation to a study of seven long bone dimensions, a new taxon-“independent” approach is suggested. For a given predictor, its taxonomic “independence” is restricted to the size range over which the body weight-predictor relationship for African apes and humans converges. Different predictors produce converging body weight estimates (BWEs) for different size ranges: taxon-“independent” estimates can be calculated for small- and medium-sized hominids (e. g., for weights below 50 kg) using femoral and tibial dimensions, whereas upper limb bones provide converging results for large hominids (above 50 kg). If the remains of Australopithecus afarensis really belong to one species, the relationship of male (above 60 kg) to female body weight (approximately 30 kg) does not fall within the observed range of modern hominoids. Considering Sts 14 (22 kg) to represent a small-sized Australopithecus africanus, the level of encephalization lies well above that of extant apes. If OH 62 (approximately 25 kg), with limb proportions less human-like than those of australopithecines, indeed represents Homo habilis (which has been questioned previously), an increase in relative brain size would have occurred well before full bipedality, an assumption running counter to current assumptions concerning early human evolution. © 1993 Wiley-Liss, Inc.     

Individual variation in body temperature and energy expenditure in response to mild cold

We studied interindividual variation in body temperature and energy expenditure, the relation between these two, and the effect of mild decrease in environmental temperature (16 vs. 22 degrees C) on both body temperature and energy expenditure. Nine males stayed three times for 60 h (2000-0800) in a respiration chamber, once at 22 degrees C and twice at 16 degrees C, in random order. Twenty-four-hour energy expenditure, thermic effect of food, sleeping metabolic rate, activity-induced energy expenditure, and rectal and skin temperatures were measured. A rank correlation test with data of 6 test days showed significant interindividual variation in both rectal and skin temperatures and energy expenditures adjusted for body composition. Short-term exposure of the subjects to 16 degrees C caused a significant decrease in body temperature (both skin and core), an increase in temperature gradients, and an increase in energy expenditure. The change in body temperature gradients was negatively related to changes in energy expenditure. This shows that interindividual differences exist with respect to the relative contribution of metabolic and insulative adaptations to cold.     

Possible “atavistic” structures in human aneuploids

Comprehensive dissections of aneuploid (trisomy 18 and 13) neonates have revealed numerous supernumerary muscles that, although present in rare individuals, do not regularly occur in the human. These supernumerary muscles include: “platysma occipitalis,” “rhomboideus occipitalis,” “deltopectoral” complex, “latissimocondyloideus,” “pectorodorsalis,” “chondrohumeralis,” and “peroneus digiti quinti”; a few muscles, e.g., palmaris longus and brevis are lacking altogether. One specimen exhibited a “linguofacial trunk” arising from the external carotid artery. The supernumerary muscles found in these aneuploid specimens are regularly found in monkeys and sometimes in the great apes. It is suggested that these supernumerary muscles may be “atavistic” structures. Problems in establishing homologies between these muscles among primates are discussed, and mechanisms leading to the development of these muscles in human aneuploids are proposed.     

Cryptic genetic variation can make “irreducible complexity” a common mode of adaptation in sexual populations

The existence of complex (multiple‐step) genetic adaptations that are “irreducible” (i.e., all partial combinations are less fit than the original genotype) is one of the longest standing problems in evolutionary biology. In standard genetics parlance, these adaptations require the crossing of a wide adaptive valley of deleterious intermediate stages. Here, we demonstrate, using a simple model, that evolution can cross wide valleys to produce “irreducibly complex” adaptations by making use of previously cryptic mutations. When revealed by an evolutionary capacitor, previously cryptic mutants have higher initial frequencies than do new mutations, bringing them closer to a valley‐crossing saddle in allele frequency space. Moreover, simple combinatorics implies an enormous number of candidate combinations exist within available cryptic genetic variation. We model the dynamics of crossing of a wide adaptive valley after a capacitance event using both numerical simulations and analytical approximations. Although individual valley crossing events become less likely as valleys widen, by taking the combinatorics of genotype space into account, we see that revealing cryptic variation can cause the frequent evolution of complex adaptations.     

Transcriptome analysis reveals the difference between “healthy” and “common” aging and their connection with age‐related diseases

A key goal of aging research was to understand mechanisms underlying healthy aging and develop methods to promote the human healthspan. One approach is to identify gene regulations unique to healthy aging compared with aging in the general population (i.e., “common” aging). Here, we leveraged Genotype‐Tissue Expression (GTEx) project data to investigate “healthy” and “common” aging gene expression regulations at a tissue level in humans and their interconnection with diseases. Using GTEx donors' disease annotations, we defined a “healthy” aging cohort for each tissue. We then compared the age‐associated genes derived from this cohort with age‐associated genes from the “common” aging cohort which included all GTEx donors; we also compared the “healthy” and “common” aging gene expressions with various disease‐associated gene expressions to elucidate the relationships among “healthy,” “common” aging and disease. Our analyses showed that 1. GTEx “healthy” and “common” aging shared a large number of gene regulations; 2. Despite the substantial commonality, “healthy” and “common” aging genes also showed distinct function enrichment, and “common” aging genes had a higher enrichment for disease genes; 3. Disease‐associated gene regulations were overall different from aging gene regulations. However, for genes regulated by both, their regulation directions were largely consistent, implying some aging processes could increase the susceptibility to disease development; and 4. Possible protective mechanisms were associated with some “healthy” aging gene regulations. In summary, our work highlights several unique features of GTEx “healthy” aging program. This new knowledge could potentially be used to develop interventions to promote the human healthspan.     

Cardiac metabolism in high performance fish

In aerobic tissues, such as cardiac and skeletal muscle, short term increases in energy demand are met primarily by acute regulation of mitochondrial pathways. Chronic increases in time-average metabolic rate of an individual or tissue can lead to modest “physiological adaptations” that may result in increased metabolic capacities and more efficient energy production and utilization. These physiological adaptations differ fundamentally from those which alter metabolic rate acutely. Analysis of the metabolic strategies used by an individual to chronically elevate cardiac metabolic rates may help identify the components of cardiac metabolism which may be constrained or malleable over evolutionary time. While pronounced physiological differences in cardiac energy transduction are apparent across species, the evolutionary origins of such differences are difficult to assess. However, the functional consequences of such differences in homologous tissues across species can be discussed with more certainty. Both chronic hypermetabolic challenges and interspecies comparisons suggest highly oxidative tissues such as heart are restricted to strategies which a) elevate the functional mass b) make more efficient use of intracellular space devoted to mitochondria and c) shift toward more efficient metabolic fuels, primarily fatty acids if oxygen delivery is not a factor.