Keeping weight off depends on carbohydrates : Pre-Maintenance & Maintenance Forum : Active Low-Carber Forums

#1 ^

Thu, Jun-28-12, 01:50

Demi

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Keeping weight off depends on carbohydrates

A new study indicates that indicates that the proportion of carbs, protein and fat may determine whether weight loss maintenance is temporary or successful:

Quote:

Keeping weight off depends on carbohydrates

Diets that are low in refined carbohydrates may help people to keep weight off longer than low-fat plans, new research suggests.

The study in Tuesday's online issue of the Journal of the American Medical Association looked at 21 men and women with an average age of 30 who'd lost an average of nearly 14 per cent of their initial weight.

Doctors and scientists are interested in finding the best ways to maintain weight loss knowing that just one in six overweight and obese adults in the U.S. said they were able to maintain weight loss of at least 10 per cent for a year in national surveys.

Study participants were randomly assigned to follow one of three diets:

A low fat diet with 60 per cent of energy from high-glycemic load carbohydrates that cause a rapid rise in blood sugar like white bread, 20 per cent from fat and 20 per cent from protein, emphasizing whole grains and a variety of fruits and vegetables.
A low glycemic index diet (40 per cent from carbohydrate, 40 per cent from fat, and 20 per cent from protein; moderate glycemic load) that replaced some processed grains and starchy vegetables with other vegetables, legumes and fruit.
Very low carbohydrate diet modelled on Atkin's (10 per cent from carbohydrate, 60 per cent from fat, and 30 per cent from protein; low glycemic load).

The participants followed the diets in random order, each for four weeks.

The researchers found energy expenditure differed for each of the diets. Resting energy expenditure is the amount of calories the body burns at rest to breathe and to keep organs like the heart and brain working.

Decreases in resting energy expenditure was greatest for the low fat diet (loss of 205 kcal/d), intermediate for low-glycemic (166 kcal/day) and lowest for the very-low carbohydrate diet (128 kcal/d), Cara Ebbeling of Children's Hospital Boston and her co-authors said.

"The results of our study challenge the notion that a calorie is a calorie from a metabolic perspective," the researchers concluded. "Total energy expenditure differed by approximately 300 kcal/d between these two diets [very low-carbohydrate vs. low-fat], an effect corresponding with the amount of energy typically expended in one hour of moderate-intensity physical activity.

"These findings suggest that a strategy to reduce glycemic load rather than dietary fat may be advantageous for weight-loss maintenance and cardiovascular disease prevention."

Metabolic changes

Successfully maintaining weight loss requires changes in behaviour and environment to stick long-term, they noted.

Although the very low-carbohydrate diet produced the greatest metabolic improvements, it also showed potentially harmful side-effects.

The low-carbohydrate diet did the best job at preserving a participant's resting energy expenditure but cortisol levels, a hormonal measure of stress, was also highest on that diet. High cortisol levels in the long term can increase blood sugar levels and add to fat stores.

Participants weren't assessed for adherence to the diets but maintenance of weight loss was tracked.

A journal editorial accompanying the study called it a well-designed study using state-of-the-art measurements.

But interpreting the results of the short-term clinical study is challenging since one diet had 10 per cent more protein than the others and since an earlier study showed that protein produces greater increases in resting energy expenditure than fat or carbohydrate, said editorialist Dr. George Bray of Pennington Biomedical Research Centre in Baton Rouge, La.

Changing dieters' behaviour

Obesity is one of the most important and frustrating problems for physicians to treat, Bray said.

"Although the exact relationship between dietary composition and weight maintenance remains unclear, calorie restriction is more important than diet composition in administering weight-loss regimens," he concluded.

A second randomized clinical trial appearing in the same issue of the Journal of the American Medical Association that involved 363 obese and overweight adults suggested that people assigned to a standard weight-loss program lost more weight than those in a stepped up program that adjusts the frequency and intensity of treatment based on weight-loss goals.

The stepped up approach cost half as much per person ($785 versus $1,357) and by the end of the study, both groups had regained some weight.

"This trial thus shows the novel approach of spending more time and effort on patients who need it most may be more economical than implementing a standard protocol for all participants regardless of their response," Bray said.

Both studies were funded by the U.S. National Institutes of Health. Ebbeling's also received funding from the New Balance Foundation.

http://www.cbc.ca/news/health/story...aintenance.html

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#2 ^

Thu, Jun-28-12, 02:26

Demi

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Quote:

Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance

Cara B. Ebbeling, PhD; Janis F. Swain, MS, RD; Henry A. Feldman, PhD; William W. Wong, PhD; David L. Hachey, PhD; Erica Garcia-Lago, BA; David S. Ludwig, MD, PhD

ABSTRACT

Context Reduced energy expenditure following weight loss is thought to contribute to weight gain. However, the effect of dietary composition on energy expenditure during weight-loss maintenance has not been studied.

Objective To examine the effects of 3 diets differing widely in macronutrient composition and glycemic load on energy expenditure following weight loss.

Design, Setting, and Participants A controlled 3-way crossover design involving 21 overweight and obese young adults conducted at Children's Hospital Boston and Brigham and Women's Hospital, Boston, Massachusetts, between June 16, 2006, and June 21, 2010, with recruitment by newspaper advertisements and postings.

Intervention After achieving 10% to 15% weight loss while consuming a run-in diet, participants consumed an isocaloric low-fat diet (60% of energy from carbohydrate, 20% from fat, 20% from protein; high glycemic load), low–glycemic index diet (40% from carbohydrate, 40% from fat, and 20% from protein; moderate glycemic load), and very low-carbohydrate diet (10% from carbohydrate, 60% from fat, and 30% from protein; low glycemic load) in random order, each for 4 weeks.

Main Outcome Measures Primary outcome was resting energy expenditure (REE), with secondary outcomes of total energy expenditure (TEE), hormone levels, and metabolic syndrome components.

Results Compared with the pre–weight-loss baseline, the decrease in REE was greatest with the low-fat diet (mean [95% CI], –205 [–265 to –144] kcal/d), intermediate with the low–glycemic index diet (–166 [–227 to –106] kcal/d), and least with the very low-carbohydrate diet (−138 [–198 to –77] kcal/d; overall P = .03; P for trend by glycemic load = .009). The decrease in TEE showed a similar pattern (mean [95% CI], −423 [–606 to –239] kcal/d; −297 [–479 to –115] kcal/d; and −97 [–281 to 86] kcal/d, respectively; overall P = .003; P for trend by glycemic load < .001). Hormone levels and metabolic syndrome components also varied during weight maintenance by diet (leptin, P < .001; 24-hour urinary cortisol, P = .005; indexes of peripheral [P = .02] and hepatic [P = .03] insulin sensitivity; high-density lipoprotein [HDL] cholesterol, P < .001; non-HDL cholesterol, P < .001; triglycerides, P < .001; plasminogen activator inhibitor 1, P for trend = .04; and C-reactive protein, P for trend = .05), but no consistent favorable pattern emerged.

Conclusion Among overweight and obese young adults compared with pre–weight-loss energy expenditure, isocaloric feeding following 10% to 15% weight loss resulted in decreases in REE and TEE that were greatest with the low-fat diet, intermediate with the low–glycemic index diet, and least with the very low-carbohydrate diet.

Many people can lose weight for a few months, but most have difficulty maintaining clinically significant weight loss over the long term. According to data from the National Health and Nutrition Examination Survey (1999-2006), only 1 in 6 overweight and obese adults report ever having maintained weight loss of at least 10% for 1 year.1 Among dietary weight-loss trials, in which reporting bias can be eliminated, the long-term success rates may be even lower.2 One explanation for the poor long-term outcome of weight-loss diets relates to behavior, in that the motivation to adhere to restrictive regimens typically diminishes with time. An alternative explanation is that weight loss elicits biological adaptations—specifically a decline in energy expenditure (adaptive thermogenesis) and an increase in hunger—that promote weight regain.

Obesity treatment should emphasize behavioral methods to foster and maintain decreased energy intake. Several recent clinical trials indicate a direct relationship between dietary adherence and weight loss, regardless of dietary treatment group assignment. However, because metabolic pathways vary in energetic efficiency, dietary composition could affect energy expenditure directly by virtue of macronutrient differences or indirectly through hormonal responses to diet that regulate metabolic pathways.

Diets that aim to attenuate the increase in blood glucose levels after eating—specifically, low–glycemic index (emphasizing carbohydrate source) and very low-carbohydrate (focusing on carbohydrate restriction) diets—have been hypothesized to confer such a “metabolic advantage.” Acutely, reducing dietary glycemic load diet may elicit hormonal changes that improve the availability of metabolic fuels in the late postprandial period, and thereby decrease hunger and voluntary food intake. Chronically, a low–glycemic load diet may attenuate the decline in resting energy expenditure (REE) that occurs during weight loss.

We conducted a controlled feeding study to evaluate the effects of 3 weight-loss maintenance diets, which encompass prevailing ranges of macronutrient composition and glycemic load (a low-fat diet, a low–glycemic index diet, and a very low-carbohydrate diet) on energy expenditure, hormones, and components of the metabolic syndrome.

http://jama.jamanetwork.com/article...ticleid=1199154

#3 ^

Fri, Jun-29-12, 08:43

Plinge

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Quote:

Originally Posted by Demi

http://jama.jamanetwork.com/article...ticleid=1199154

This study is useful for comparing three eating "styles", but I don't think it can be used, except vaguely, as evidence for fat v carbohydrate conclusions (it wasn't designed to that end), because the diets contain so many variables.

I don't know exactly what was in the diets, but since the study says that the middle diet was a Lower Glycaemic Index diet than the low-fat diet, the low-fat diet would therefore be more quickly digestible. Food that is more easily digestible makes fewer demands on the metabolism, so that would explain the results for me. Presumably, the low-fat diet, which includes wheat products, contains more processed food--since all wheat products are processed. The low-carb diet contains more nuts, meat, etc., which require considerable digestive effort, explaining, in my opinion, why that diet had the highest metabolic effect of the three.

The researchers' full discussion, which I've now read in the PDF of the study, goes round the houses a bit in trying to explain their findings. At one point they touch on the following possible mechanism:

"Alternative explanations for the observed differences in Resting Energy Expenditure and Total Energy Expenditure may involve intrinsic effects of dietary composition on the availability of metabolic fuels ..."

But they leave it at that. As anyone who has read my ramblings on maintenance knows, I'm convinced that differences in degree of calorie availability are an overlooked factor in metabolism. Put simply, it takes less effort for the body to extract, say, a protein from a glass of skimmed milk than from a steak.

Last edited by Plinge : Fri, Jun-29-12 at 09:28.

#4 ^

Fri, Jun-29-12, 10:14

MizKitty

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The parts about which diet resulted in the least decrease in resting energy expenditure were interesting.

#5 ^

Fri, Jun-29-12, 11:06

Plinge

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Quote:

Originally Posted by MizKitty

The parts about which diet resulted in the least decrease in resting energy expenditure were interesting.

I'm surprised these authors discount the influence of digestion on resting energy expenditure. This bit:

"The thermic effect of food (the increase in energy expenditure arising from digestive and metabolic processes) dissipates in the late postprandial period and would not affect REE measured in the fasting state."

We all know that meat and nuts, and certain other low-carb foods, can take a long time to digest. The food in the study's low-fat diet, with its high glycaemic index, will digest more quickly, lowering the body's average energy expenditure in comparison to that on meals which take longer to digest. The thermic effect of digestion would surely impinge on resting energy expenditure, explaining why it was higher on the two less glycaemic diets.

I wonder what the authors consider "the late postprandial period". The thermal effect of food may continue for many hours. I've just been reading one study in which it was measured for six (Barr and Wright, Postprandial energy expenditure in whole-food and processed-food meals: implications for daily energy expenditure, 2010). In 24 hours, allowing a six-hour gap between meals for the thermal effect of food to dissipate would leave only six hours to sleep. In my experience, if I eat a steak, digestive energy expenditure might continue much longer than six hours--I can sometimes sense it into the next day. Unlike the authors, I definitely suspect a connection between the digestive energy cost of the three diets and the levels of recorded energy expenditure, including resting energy expenditure.

Last edited by Plinge : Fri, Jun-29-12 at 11:15.

#6 ^

Sun, Jul-01-12, 05:31

Demi

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From Dr Berkeley over at Refuse to Regain:

Quote:

June 30, 2012

JAMA Study Confirms Maintenance Benefits of Low Carb Diet

By Barbara Berkeley, MD

The debate about whether a calorie is a calorie rages on, but not I think, in the minds of most successful weight maintainers. The same may be said for successful dieters who reflexively cut carbohydrates from their menu when they start a weight loss plan. While their thought may be to reduce calories, something quite different may be occurring when they ditch the bread and pasta for meals of chicken breast and salad.

Too few scientific studies have looked at the metabolic differences that occur in response to differing nutrients. Some readers may find my continued harping on the insulin system simplistic, but it has been my way of conceptualizing a consistent observation: limiting carbohydrate in the diet to natural fruit and vegetable sources appears to decrease hunger, clamp down on cravings, preserve weight maintenance, and promote health. While I am well aware of those readers who say that they do perfectly well eating other carbs, I still think that they are likely to represent a minority. In my own experience, there is nothing so threatening to the maintenance of long term weight as a return to modern carb consumption. When patients come back to me with a significant regain, there has uniformly been a reassertion of carbs and carb craving in their lives.

The June 27th issue of JAMA has a study that comes from researchers at Harvard and Baylor . It is neatly done and quite thought provoking. The idea was to induce about a 13% weight loss in overweight men and women. These would-be maintainers were then placed on one of three diets whose calories were calculated to preserve that weight loss. But the types of calories in each diet were different and were constructed to follow one of three models. Each study subject was given each of the three diets in turn, with the order of the diets being random.

The maintenance diets were as follows:

Low Fat: This diet followed the more traditionally prescribed guidelines for weight control being low in fat and high in whole grains, fruits and vegetables. (60% carbs/20% Fat/20% protein)

Low Glycemic Index: This diet actually achieved a moderate (not low) glycemic load by replacing some grains and starches with healthy fats, fruits, vegetables and legumes. (40% carbs/ 40% fat/ 20% protein)

Very Low Carbohydrate: This diet was modeled on the Atkins diet. (10% carbs/ 60% fat/ 30% protein)

Each diet was eaten in random order for four weeks. The subjects were tested to determine whether their metabolic rate (the speed and efficiency of calorie burn) was affected by the varying nutrient compositions. They were also evaluated for insulin sensitivity, cortisol, leptin, thyroid hormone, and subjective levels of hunger and satisfaction among a number of other parameters.

The fascinating result was that both resting and total metabolic rate was significantly greater when people ate the very low carb diet. In fact, the difference in metabolic advantage between the low fat and low carb diet was about 300 calories per day, “an effect corresponding with the amount of energy typically expended in 1 hour of moderate-intensity physical activity.”

In addition, the study revealed a number of other beneficial advantages to the low-carb diet. These included better sensitivity to the action of insulin, and improvement in markers for metabolic syndrome. Leptin is a hormone which is often invoked as a reason for failed maintenance. Leptin should theoretically decrease food intake and one would assume that higher levels would be a good thing. However we know that obese people (and obese lab animals too) have a resistance to leptin. Levels may be high but they don’t work appropriately. In this study, leptin levels were lowest in the low carb group, but leptin sensitivity appeared to be restored by eating this way.

There were two negatives to the low carb diet, both related to inflammatory stress. Two stress markers were elevated in this diet: cortisol and C Reactive Protein. However, the diet used for the low carb choice was a 60% fat plan based on Atkins. We know that certain fats, particularly saturated fats, can be proinflammatory. Once again, there was no testing of another kind of low carb diet: a primal style diet that eliminates grains and starches but preserves fruits and vegetables and which uses lower fat protein choices. I don’t need to tell you that my belief is that this diet would have triumphed over the others.

But enough of my biases. We finally have a study that shows that different foods create different responses in the body and that calories are only one property of food. The other properties of food can easily trump calories by activating differing pathways through digestion and metabolism.

A calorie is just a calorie that’s true, but unlike what we’ve been led to believe, it is not the be all and end all of how the body burns or stores food. Can we finally begin to get past this simplistic and unhelpful maxim?

http://refusetoregain.com/refusetor...-carb-diet.html