Of all of the common complications of obesity, fatty liver disease is perhaps the most insidious. Often starting without clinical symptoms and little more than a mild increase in liver enzymes, it can progress to inflammation, fibrosis, cirrhosis and ultimate liver failure. It can also markedly increase the risk for hepatocellular cancer even in patients who do not progress to cirrhosis.
Now, a paper by Mary Rinella from Northwestern University, Chicago, published in JAMA provides a comprehensive overview of what we know and do not know about early detection and management of this condition.
The findings are based on a review of 16 randomized clinical trials, 44 cohort or case-control studies, 6 population-based studies, and 7 meta-analyses.
Overall between 75 million and 100 million individuals in the US are estimated to have nonalcoholic fatty liver disease with 66% of individuals older than 50 years with diabetes or obesity having nonalcoholic steatohepatitis with advanced fibrosis.
Although the diagnosis and staging of fatty liver disease requires a liver biopsy, biomarkers (e.g. cytokeratin 18) may eventually help in the detection of advanced fibrosis.
In addition, non-invasive imaging techniques including vibration-controlled transient elastography, ultrasound with acoustic radiation force impulse or even magnetic resonance elastography are fairly accurate in the detection of hepatic fibrosis and are the most reliable modalities for the diagnosis of advanced fibrosis (cirrhosis or precirrhosis).
Currently, weight loss is the only proven treatment for fatty liver disease. Pharmacotherapy including treatment with vitamin E, pioglitazone, and obeticholic acid may also provide some benefit (none of these treatments currently are approved for this indication by the UD FDA). Futhermore, the potential benefits of existing and emerging anti-obesity treatments on the incidence and progression of fatty liver remains to be established.
As Rinella points out,
“It is important that primary care physicians, endocrinologists, and other specialists be aware of the scope and long-term effects of the disease.”
Clearly, screening for fatty liver disease needs to be part of every routine work up of individuals presenting with excess weight.
This is why the recent paper by Nia Mitchell and colleagues from the University of Colorado, published in the American Journal of Preventive Medicine is of considerable interest.
The study looks at long-term weight loss of participants who joined Take Off Pounds Sensibly (TOPS), a US nonprofit, low-cost, peer-led weight-loss program between 2005-2011 (207,469 individuals) and consecutively renewed their annual membership at least once 74,629 (35.9%).
Mean weight loss for those who renewed their membership at least once was 6% and 8% for the 2,289 participants with 7 years of consecutive annual renewal.
Three points are probably worth emphasizing: for one, as with most weight loss programs, only a small proportion of individuals stick with it even for just a year (in this case about 35% which is still probably better than for most programs that I am aware of). Long-term members (in this case about 10%, who manage to stick with the program for at least 7 years) are even a greater minority.
Secondly, those who stick with the program in the long-term are able to sustain their benefit – of course it is hard to prove that this long-term benefit is actually causally related to the program – after all, the kind of people who make long-term commitments to a weight management program may well differ from the general public in other ways that may be important for their success.
Thirdly, the study illustrates that the average weight loss even for those who stick with the program over 7 years manage to keep off only about half of what is generally seen in long-term studies with bariatric surgery (about 20% weight loss over 15-20 years).
None of this takes away from the success of the TOPS approach to long-term weight management – it does however illustrate that even one of the best and longest running “lifestyle” management approaches to weight management, faces the usual challenges of attrition and plateauing weight loss at a level that may be less than what many living with severe obesity would consider a satisfactory outcome.
Kudos to TOPS for allowing this public analysis of their data – few other weight loss programs would dare to do the same.
Note: see comment #1
One of the most persistent notions about equating caloric deficit to weight loss is the 3500 Cal “rule”.
I have previously posted about why this is nonsense and not exactly helpful when it comes to thinking about clinical weight loss or weight (you’re dealing with physiology NOT physics!).
Now, Nicholas Gwerder, a student from the University of Sacramento, in his Master Thesis, has apparently reviewed the literature on this and concludes that if anything, one pound of weight loss comes closer to 4,500 calories.
Gwerder reaches this conclusion by analysing data from 28 studies in which he compares the theoretical weight loss to the actual weight (and fat) lost in these studies.
Although, I do not have access to Gwerder’s Master Thesis, here is what he says in the summary:
“The energy equivalent of body weight loss varied considerably, dependent upon the constituent portions of fat, water, protein, carbohydrate and mineral lost. Adipose tissue also varied with type and was dependent upon the composition of lipid, water, and protein. The most valid theoretical equivalent for a pound of fat was calculated at 4,423.90 kilocalories based on in vivo extraction of human intracellular lipid samples.”
Thus, as Gwerder points out, the 3,500 per pound notion tossed around (including by a number of guidelines and associations)
“…severely underestimates the caloric values needed to achieve desired fat mass loss. This use of the proper caloric value for fat mass loss has the potential to improve exercise and nutrient recommendations for achieving healthy body fat values.”
Thus, if this number holds true, a daily 500 Cal deficit maintained over 10 weeks will not give you a 10 pound weight loss, but rather only about 7.5 lbs.
All the same, in practice over time this never really works out, not just because of the individual variability (Gwerder notes about 20% variation in this relationship) but because as you reduce your caloric intake, your individual metabolic requirements will very quickly shift to living off fewer calories, which means that pretty soon into your diet, the initial 500 Cal deficit is no longer a deficit (thank your physiology). This is the feared weight-loss plateau – the frustration of every dieter.
So, whether 3,500 or 4,500 Cal per pound, the relationship between calorie restriction and weight loss is not linear and thus extrapolating the amount of expected weight loss based on this deficit seldom works out in practice.
Indeed, I know from my patients that this “rule” is a matter of endless frustration and seldom helpful.
Managing weight is not simply about energy in and energy out.
And finally, to conclude this week’s discussion of evidence to support the notion that weight cycling predicts weight (fat) gain especially in normal weight individuals, I turn back to the paper by Dulloo and colleagues published in Obesity Reviews, which quotes these interesting findings in US Rangers:
“…U.S. Army Ranger School where about 12% of weight loss was observed following 8–9 weeks of training in a multi-stressor environment that includes energy deficit. Nindl et al. reported that at week 5 in the post-training recovery phase, body weight had overshot by 5 kg, reflected primarily in large gains in fat mass, and that all the 10 subjects in that study had higher fat mass than before weight lost. Similarly, in another 8 weeks of U.S. Army Ranger training course that consisted of four repeated cycles of restricted energy intake and refeeding, Friedl et al. showed that more weight was regained than was lost after 5 weeks of recovery following training cessation, with substantial fat overshooting (∼4 kg on average) representing an absolute increase of 40% in body fat compared with pre-training levels. From the data obtained in a parallel group of subjects, they showed that hyperphagia peaked at ∼4 weeks post-training, thereby suggesting that hyperphagia was likely persisting over the last week of refeeding, during which body fat had already exceeded baseline levels.”
Obviously, association (even in a prospective cohort) does not prove causality or, for that matter, provide insights into the physiological mechanisms underlying this observation.
All we can conclude, is that these observations in US Rangers (and the other studies cited in Dulloo’s article) are consistent with the notion that weight loss in normal weight individuals can be followed by significant weight gain, often overshooting initial weight.
Incidentally, these findings are also consistent with observational studies in women recovering from anorexia nervosa, famine, cancer survivors and other situations resulting in significant weight loss in normal weight individuals.
Certainly enough evidence to consider a work of caution against “recreational” weight loss, especially in individuals of normal weight.
Dulloo AG, Jacquet J, Montani JP, & Schutz Y (2015). How dieting makes the lean fatter: from a perspective of body composition autoregulation through adipostats and proteinstats awaiting discovery. Obesity reviews : an official journal of the International Association for the Study of Obesity, 16 Suppl 1, 25-35 PMID: 25614201
Regular readers will be well of the very real social and health impact of weight bias and discrimination.
Now, Sara Kirk of Dalhousie University, Halifax, NS, invites you to join her free Massive Open Online Course (MOOC), on weight bias and stigma in obesity, which will be starting on April 20th 2015 (just a week before the Canadian Obesity Summit in Toronto).
The course builds on Kirk’s extensive research in this area and the dramatic presentation that was created from her findings.
Participants will be able to explore some of the personal and professional biases that surround weight management and that impact patient care and experience.
This will hopefully give health professionals better insight into how to approach individuals experiencing obesity in a respectful and non-judgmental manner and provide strategies to build positive and supportive relationships between health care providers and patients.
While targeted at health care providers, the course should also be of interest to anyone interested in learning more about what weight bias is and how it can impact health and relationships.
Participants who complete the course requirements can apply for a citation of completion (for a nominal fee).