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Weight loss: Are calories less important than food patterns?

{For personal reasons, mainly involving the restoration of an 1843 cottage in Dublin’s south coastal village of Blackrock, I have been absent from blogging for a while. I’m back now with renewed vigour to pursue the best of nutrition science and to tackle, mercilessly, nutribabble.}

 One of the latest trends in nutrition is to reduce our focus on nutrients and to sharpen our focus on the role of particular food patterns in promoting health. High up on the list of foods to avoid are processed (or ultra-processed) foods or foods high in fats, refined sugars and salt. A recent paper from Stanford University has been widely cited (not by the authors) as evidence that advice on caloric intake is less important in weight loss than the quality of the diet consumed[1]. In this study which was well designed, with adequate statistical power and ample duration, the authors describe the advice given to subjects (all were obese) thus: “No explicit instructions for energy (kilocalories) restriction were given. Both diet groups were instructed to (1) maximize vegetable intake; (2) minimize intake of added sugars, refined flours, and trans fats; and (3) focus on whole foods that were minimally processed, nutrient dense, and prepared at home whenever possible.” There were two treatment groups: a high-carbohydrate, low-fat diet and the opposite, a high-fat, low-carbohydrate diet. The two groups were given dietary advice to achieve the food pattern outlined above. Both groups lost weight after the 12 moths of intervention to the level of about 5.5 ( lbs) on average.

Here is how the New York Times reported the findings (Anahad O’Connor February 8th, 2018): Anyone who has ever been on a diet knows that the standard prescription for weight loss is to reduce the amount of calories you consume. But a new study, published … in JAMA, may turn that advice on its head. It found that people who cut back on added sugar, refined grains and highly processed foods while concentrating on eating plenty of vegetables and whole foods — without worrying about counting calories or limiting portion sizes — lost significant amounts of weight over the course of a year”. A distinguished Dean from Tufts in Boston was quoted as saying: “The research lends strong support to the notion that diet quality, not quantity, is what helps people lose and manage their weight most easily in the long run. It also suggests that health authorities should shift away from telling the public to obsess over calories and instead encourage Americans to avoid processed foods that are made with refined starches and added sugar, like bagels, white bread, refined flour and sugary snacks and beverages”.  The NYT piece was quoted across the globe by lazy editors to fill column inches with a pretty impressive story. Regrettably, it was a misleading story which opted to hide from its readers one awfully important point.

You see, the JAMA paper gives data on caloric intake at the beginning of the study and also at 3, 6 and 12 months of the intervention. Right throughout the study, irrespective of which of the two diets were being followed, no differences were seen between the two groups in calorie intake. So, for convenience of communication, I’ll give the average values of the two treatments at the different times. At baseline, the average daily caloric intake was 2150. By month 3, it had fallen to 1580. It then rose to 1620 by month 6 and at the 12 month conclusion, it was 1700. Thus, the 12 month figure was all of 450 fewer calories consumed
every day. The average body mass index (BMI; kg/m2) was 33, which means that the two groups were well into the obesity category of body weight. At that body weight and that daily caloric deficit from food alone, weight loss was no miraculous discovery. Which raises now a few questions.

Why were readers of the New York Times (NYT) misled so as to believe that calories don’t matter in weight loss? Is it so obvious to the NYT that the food patterns recommended were somehow so bound to lead to a caloric deficit that it needn’t be mentioned to its readers? Or is it remotely possible that the NYT never really read the paper and thus missed this whopping caloric deficit? I doubt I’ll ever know the answer. But if I was a journalist, I would be inclined to poke a bit further into this paper. We know from the paper that there was considerable variability in weight loss but no data are given. We also are not given any data about the changes that occurred in food intake , particularly to provide supporting data on the target foods (less of the sugary type, more of the complex carbohydrate food, more vegetables etc.). But the big question is why was the average relapse so low? Thus at three months, the mean daily caloric intake was 1580 and by month 12, it had slipped back a bit but only to 1700 kcal per day, a 9-month average regain of just 120 kcal per day. The human body absolutely defends a prevailing weight such that as all dieters know, the maintenance of weight loss requires enormous perseverance. Take your eye off the tiller for one moment and the tidal wave of our obesogenic environment will sweep you back on the rocks. So why not on this diet? I don’t know the answer to that but I do know that the anti-processed food lobby will argue that it is proof that processed food fosters a false appetite and that once that is taken away with a change to minimally processed home prepared foods, appetite regulation returns and low energy intakes are the result. There is however a little fly in the ointment here from another paper which set out to study the link between the intake of ‘ultra-processed foods’ and cancer[2].

This study from France used a cohort recruited through the Internet and who had their diet analysed through digital interaction using a multiple pass 24-hour recall. In all, 104,980 subjects were eligible to participate and did so over the period  2009-1017. The study was about cancer and that will not feature in this blog. Rather, we will focus on the weight of these subjects expressed as BMI (kg/m2). The population was divided into quartiles according to the contribution (weight by weight) of ultra-processed foods to overall food intake. The respective contributions (% w/w) of ultra- processed foods to the diets of the French subjects were thus: Q1 = 9; Q2 = 14 ; Q3 = 20 and Q4 = 32. And across this spectrum of ultra-processed food intake, BMI remained constant to the first decimal point at 23.8 kg/m2. The literature abounds in studies linking ultra-processed foods to obesity. Mais apparemment, pas en France. (But apparently, not in France).

So returning to the Stanford study, we have no differences in weight loss between those on a low fat-high carbohydrate diet as opposed those on a high fat-low carbohydrate diet over a 12 month period. They showed precisely the same caloric deficit over that period so one concludes that it simply doesn’t matter what advice one is given for a reduction in fat or in carbohydrate, the bottom line is that if that advice leads to a calorie deficit, then weight loss will accrue, irrespective of what the NYT might say. Quite how there was so little mean relapse in this study is as yet unexplained but as mentioned above, the anti-processed food advocates will argue that the abandonment of such foods returns people to a diet where appetite control in returns. The fly in the ointment of the French paper will never be raised.

Fine up to a point. However,  a previous NIH funded study, the “Pounds Lost Study” with weight loss programmes varying in fat and carbohydrate and reaching a similar conclusion to the Stanford study, showed a steady weight loss to 12 months with a significant weight loss relapse thereafter[3]. My calculation of the data presented in the tables of the Stanford study is that the average resting metabolic rate might be about 1,450 kcal per day which might not seem a million miles from the reported energy intake at 12 months, 1,700 kcal. However, the former is calculated based on weight stability but with dieting, this will fall by about 15%[4] to 1,230 kcal/d. Either these people will continue to lose weight or that deficit will drive a weight regain process. All the available science would show a slow relenting return to original bodyweight in a large proportion of the population. Maybe the Stanford study will show that better investment in food choice and tutoring on home cooking might help. Here’s hoping it does.

This Stanford study is very well designed, well executed and fairly reported. More data on food intake (% consumers and consumer only intake) would have been welcome but there’s only so much one can do for modern journals with page restrictions and charges. It adds significantly to the data on the relative role of the main energy macronutrients (carbohydrate & fat) and it is consistency with existing data. Regrettably, it will be long cited out of context as the study which showed that its diet quality that counts, not calories.

[1] Christopher D. Gardner, PhD; John F. Trepanowski, PhD; Liana C. Del Gobbo, PhD; Michelle E. Hauser, MD;
Joseph Rigdon, PhD; John P. A. Ioannidis, MD, DSc; Manisha Desai, PhD; Abby C. King, PhD . Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion  The DIETFITS Randomized Clinical Trial. JAMA. 2018;319(7):667-679. doi:10.1001/jama.2018.0245

[2] Thibault Fiolet, Bernard Srour, Laury Sellem,  Emmanuelle Kesse-Guyot, Benjamin Allès, Caroline
Méjean,Mélanie Deschasaux, Philippine Fassier, Paule Latino-Martel,Marie Beslay, Serge Hercberg,, Céline Lavalette, Carlos A Monteiro, Chantal Julia, Mathilde Touvier; Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort; BMJ 2018;360:k322 | doi: 10.1136/bmj.k322

[3] Frank M. Sacks, M.D., George A. Bray, M.D., Vincent J. Carey, Ph.D., Steven R. Smith, M.D., Donna H. Ryan, M.D., Stephen D. Anton, Ph.D., Katherine McManus, M.S., R.D., Catherine M. Champagne, Ph.D., Louise M. Bishop, M.S., R.D., Nancy Laranjo, B.A., Meryl S. Leboff, M.D., Jennifer C. Rood, Ph.D., Lilian de Jonge, Ph.D., Frank L. Greenway, M.D., Catherine M. Loria, Ph.D., Eva Obarzanek, Ph.D., and Donald A. Williamson, Ph.D.
Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates; N Engl J Med 2009;360:859-73
[4] Erin Fothergill, Juen Guo, Lilian Howard, Jennifer C. Kerns, Nicolas D. Knuth, Robert Brychta, Kong Y. Chen, Monica C. Skarulis, Mary Walter, Peter J. Walter, Kevin D. Hal; Persistent metabolic adaptation 6 years after “The Biggest Loser” competition; Obesity (2016) 24, 1612-1619. doi:10.1002/oby.21538


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