Category Archives: Low-Carb Eating

Low-carbohydrate diets help many folks, but not all, lose excess fat weight. When low-carb diets help, it may be related to Total Energy Expenditure (TEE). When you read “energy,” think calories. TEE is a combination of calories needed for 1) basic life processes (i.e., basal metabolic rate, as needed to maintain heart beats, breathing, steady body heat, growth and repair of tissues, etc.), 2) processing of ingested food (dietary thermogenesis), and 3) physical exercise.

Here’s the abstract of an article in The Journal of Nutrition that examines the headline question. It’s complicated and I haven’t read the full study yet.

Many obesity experts believe that to lose excess fat weight, you have to ingest fewer calories than you burn on a daily basis for physical exercise and basal metabolic rate. This creates a calorie (energy) deficit. Your body satisfies that deficit by converting fat tissue to weightless energy. The authors of the study at hand are essentially saying that, after 2-3 weeks, a low-carb diet “revs up your metabolism” to burn more calories. That can help you lose weight or maintain weight loss, unless you over-eat.

Here you go, nutrition nerds:

Background

The effect of macronutrient composition on total energy expenditure (TEE) remains controversial, with divergent findings among studies. One source of heterogeneity may be study duration, as physiological adaptation to lower carbohydrate intake may require 2 to 3 wk.

Objective

We tested the hypothesis that the effects of carbohydrate [expressed as % of energy intake (EI)] on TEE vary with time.

Methods

The sample included trials from a previous meta-analysis and new trials identified in a PubMed search through 9 March 2020 comparing lower- and higher-carbohydrate diets, controlled for EI or body weight. Three reviewers independently extracted data and reconciled discrepancies. Effects on TEE were pooled using inverse-variance-weighted meta-analysis, with between-study heterogeneity assessed using the I2 statistic. Meta-regression was used to quantify the influence of study duration, dichotomized at 2.5 wk.ResultsThe 29 trials ranged in duration from 1 to 140 d (median: 4 d) and included 617 participants. Difference in carbohydrate between intervention arms ranged from 8% to 77% EI (median: 30%). Compared with reported findings in the prior analysis (I2 = 32.2%), we found greater heterogeneity (I2 = 90.9% in the reanalysis, 81.6% in the updated analysis). Study duration modified the diet effect on TEE (P < 0.001). Among 23 shorter trials, TEE was reduced on lower-carbohydrate diets (−50.0 kcal/d; 95% CI: −77.4, −22.6 kcal/d) with substantial heterogeneity (I2 = 69.8). Among 6 longer trials, TEE was increased on low-carbohydrate diets (135.4 kcal/d; 95% CI: 72.0, 198.7 kcal/d) with low heterogeneity (I2 = 26.4). Expressed per 10% decrease in carbohydrate as %EI, the TEE effects in shorter and longer trials were −14.5 kcal/d and 50.4 kcal/d, respectively. Findings were materially unchanged in sensitivity analyses.

Conclusions

Lower-carbohydrate diets transiently reduce TEE, with a larger increase after ∼2.5 wk. These findings highlight the importance of longer trials to understand chronic macronutrient effects and suggest a mechanism whereby lower-carbohydrate diets may facilitate weight loss.

Source: Do Lower-Carbohydrate Diets Increase Total Energy Expenditure? An Updated and Reanalyzed Meta-Analysis of 29 Controlled-Feeding Studies | The Journal of Nutrition | Oxford Academic

In the Discussion section the authors write:

This finding supports a prediction of the carbohydrate-insulin model and suggests a mechanism whereby dietary carbohydrate reduction could aid in the prevention and treatment of obesity. According to this model, the high insulin-to-glucagon ratio with a diet high in glycemic load (mathematical product of glycemic index and carbohydrate amount) shifts the partitioning of metabolic fuels from oxidation in lean tissue to storage in adipose tissue. If the effects observed here persist over the long term, then reducing dietary carbohydrate intake by half from 60% of energy intake (a typical level for low-fat diets) would increase energy expenditure by ∼150 kcal/d, counterbalancing (if not compensated for by other factors) much of the secular increase in energy intake thought by some to underlie the obesity epidemic.

Steve Parker, M.D.

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Julia Belluz has interesting article at Vox regarding low-fat and low-carb diet success over the course of 12 months. Her focus is on a few individuals who participated and were outliers.

As I read this, I was reminded that successful long-term weight management starts and ends in the kitchen. It also took me back to 2009, when I determined that low-carb diets were just as legitimate as low-fat.

I don’t recall the author mentioning the typical pattern with 12-month weight loss studies: most folks lose significant weight in the first few month, then at six months they start gaining it back. Cuz they go back to their old eating habits. Sure, diets don’t work………..if you don’t follow them.

From Ms. Belluz:

As a longtime health reporter, I see new diet studies just about every week, and I’ve noticed a few patterns emerge from the data. In even the most rigorous scientific experiments, people tend to lose little weight on average. All diets, whether they’re low in fat or carbs, perform about equally miserably on average in the long term.

But there’s always quite a bit of variability among participants in these studies.Just check out this chart from a fascinating February study called DIETFITS, which was published in JAMA by researchers at Stanford.

The randomized controlled trial involved 609 participants who were assigned to follow either a low-carb or a low-fat diet, centered on fresh and high-quality foods, for one year. The study was rigorous; enrollees were educated about food and nutrition at 22 group sessions. They were also closely monitored by researchers, counselors, and dietitians, who checked their weight, waist circumference, blood pressure, cholesterol, and other metabolic measures throughout the year.

Overall, dieters in both groups lost a similar amount of weight on average — 11 pounds in the low-fat group, 13 pounds in the low-carb group — suggesting different diets perform comparably. But as you can see in the chart, hidden within the averages were strong variations in individual responses. Some people lost more than 60 pounds, and others gained more than 20 during the year.

Read the whole thing. It’s not long.

Source: Why do dieters succeed or fail? The answers have little to do with food. – Vox

The DIETFITS Trial

That’s a guacamole deviled egg.
Photo Copyright: Steve Parker

In 2014 Howard Stern interviewed Bryan Cranston and asked how he lost weight so quickly for his role as Walter White on Breaking Bad:

“Stern: When you had chemo and was getting sick playing the part of Walter White, in order to go through rapid weight loss you deliberately didn’t eat for 10 days? True or false?

Cranston: False.

Stern: How’d you lose all that weight?

Cranston: No carbohydrates. I just took out all the carbohydrates.

Stern: How much weight did you drop?

Cranston: 16 pounds, in ten days.

Stern: Painful?

Cranston: No. The first three days are really hard, ’cause your body’s changing and craving sugar and wants, you know, and then you deprive it of the sugar and it starts burning fat.”

Source: How Walter White lost weight in Breaking Bad, it wasn’t chemo – High Steaks

h/t Tom Naughton