Saturday, September 20, 2014

Some Science on Low-Carb Diets

The 'tl;dr' summary here is that basically, with relatively minor caveats, scientific studies generally increasingly seem to show low-carb diets to be either as good or better than alternatives, for both weight loss, and other health markers:

[Added 2016] The effects of ketogenic dieting on skeletal muscle and fat mass
"Lean body mass increased to a greater extent in the VLCKD [
Very low carbohydrate (<5 %), high fat (>70 %) ketogenic diets] ... as compared to the traditional group. Ultrasound determined muscle mass increased to a greater extent in the VLCKD group ... as compared to the traditional western group. Finally fat mass decreased to a greater extent in the VLCKD group"
[Rauch et al, Journal of the International Society of Sports Nutrition. 2014;11(Suppl 1):P40]

[Added 2015] Dietary Intervention for Overweight and Obese Adults: Comparison of Low-Carbohydrate and Low-Fat Diets. A Meta-Analysis
October 2015
"The probability of greater weight loss associated with low carbohydrate was >99% while the reduction in predicted risk favoring low carbohydrate was >98% … LoCHO diet was associated with modest but significantly greater improvements in weight loss and predicted ASCVD risk"
[Sackner-Bernstein J, Kanter D, Kaul S (2015) Dietary Intervention for Overweight and Obese Adults: Comparison of Low-Carbohydrate and Low-Fat Diets. A Meta-Analysis. PLoS ONE 10(10): e0139817. doi:10.1371/journal.pone.0139817]

[Added 2015] Effect of low-fat diet interventions versus other diet interventions on long-term weight change in adults: a systematic review and meta-analysis
December 15
"In weight loss trials, low-carbohydrate interventions led to significantly greater weight loss than did low-fat interventions … Low-fat interventions did not lead to differences in weight change compared with other higher-fat weight loss interventions … and led to a greater weight decrease only when compared with a usual diet … In weight loss trials, higher-fat weight loss interventions led to significantly greater weight loss than low-fat interventions"
[Tobias, Deirdre K et al., The Lancet Diabetes & Endocrinology , Volume 3 , Issue 12 , 968 - 979]

Both a Mediterranean diet and diets low in available carbohydrates protect against type 2 diabetes, study suggests
August 15, 2013
"New research shows that a Mediterranean-style diet and diets low in available carbohydrates can offer protection against type 2 diabetes"

Comparison of named diet programs finds little difference in weight loss outcomes
September 2, 2014
"In an analysis of data from nearly 50 trials including about 7,300 individuals, significant weight loss was observed with any low-carbohydrate or low-fat diet, with weight loss differences between diet programs small, findings that support the practice of recommending any diet that a patient will adhere to in order to lose weight"
[JAMA - Journal of the American Medical Association]

Cut down on 'carbs' to reduce body fat, study authors say
June 24, 2011
"A modest reduction in consumption of carbohydrate foods may promote loss of deep belly fat, even with little or no change in weight, a new study finds"
[The Endocrine Society]

Cutting carbs is more effective than low-fat diet for insulin-resistant women, study finds
June 21, 2010
"Obese women with insulin resistance lose more weight after three months on a lower-carbohydrate diet than on a traditional low-fat diet with the same number of calories"
[The Endocrine Society]

Dieting? Study challenges notion that a calorie is just a calorie
June 26, 2012
"The study finds diets that reduce the surge in blood sugar after a meal -- either low-glycemic index or very-low carbohydrate -- may be preferable to a low-fat diet for those trying to achieve lasting weight loss"
[Children's Hospital Boston / Journal of American Medical Association]

Intermittent, low-carbohydrate diets more successful than standard dieting, study finds
December 8, 2011
"An intermittent, low-carbohydrate diet was superior to a standard, daily calorie-restricted diet for reducing weight and lowering blood levels of insulin, a cancer-promoting hormone" … "Researchers at Genesis Prevention Center at University Hospital in South Manchester, England, found that restricting carbohydrates two days per week may be a better dietary approach than a standard, daily calorie-restricted diet for preventing breast cancer and other diseases"

Limiting carbs, not calories, reduces liver fat faster, researchers find
April 19, 2011
"Curbing carbohydrates is more effective than cutting calories for individuals who want to quickly reduce the amount of fat in their liver, researchers report"
[UT Southwestern Medical Center]

Limiting carbs could reduce breast cancer recurrence in women with positive IGF1 receptor
June 10, 2014
"Dartmouth researchers have found that reducing carbohydrate intake could reduce the risk of breast cancer recurrence among women whose tumor tissue is positive for the IGF-1 receptor"
[The Geisel School of Medicine at Dartmouth / Cancer Epidemiology Biomarkers & Prevention]

Losing belly fat, whether from a low-carb or a low-fat diet, helps improve blood vessel function
March 13, 2012
"Overweight people who shed pounds, especially belly fat, can improve the function of their blood vessels no matter whether they are on a low-carb or a low-fat diet, according to a new study" … "… participants on the low-carb diet lost more weight and at a faster pace, on average, which has also been seen in several other studies. He says eating higher amounts of carbohydrates can slow down the rate of body fat loss while on a weight reduction diet."
[Johns Hopkins Medicine]

Low-carb, higher-fat diets add no arterial health risks to obese people seeking to lose weight, studies suggest
June 2, 2011
"Overweight and obese people looking to drop some pounds and considering one of the popular low-carbohydrate diets, along with moderate exercise, need not worry that the higher proportion of fat in such a program compared to a low-fat, high-carb diet may harm their arteries, suggests a pair of new studies by heart and vascular researchers at Johns Hopkins"
[Johns Hopkins Medical Institutions]

Low-carbohydrate, high-protein diets may reduce both tumor growth rates and cancer risk
June 15, 2011
"Eating a low-carbohydrate, high-protein diet may reduce the risk of cancer and slow the growth of tumors already present, according to a new study" [IN MICE] … "The study was conducted in mice, but the scientists involved agree that the strong biological findings are definitive enough that an effect in humans can be considered"
[American Association for Cancer Research]

Low-carbohydrate diet reduced inflammation in study
May 8, 2014
"A low-carbohydrate diet, but not a low-fat diet, reduces inflammation in patients with type 2 diabetes, according to research. It is known that patients with type 2 diabetes have higher levels of inflammation than those who do not have the disease, and it is believed that this may contribute to a higher risk of cardiovascular disease and other complications"
[Linköping Universitet / Annals of Medicine]

Low-Carbohydrate Diets
"There is some evidence that a low-carbohydrate diet may help people lose weight more quickly than a low-fat diet and may help them maintain that weight loss ...

POUNDS LOST ... a two-year head-to-head trial comparing different weight loss strategies, found that healthy diets that varied in the proportions of different macronutrients (carbohydrates, protein and fats) worked equally well in the long run, and that there was no speed advantage for one diet over another ...

The DIRECT study compared low-carb, low-fat, and Mediterranean-style diets and found that after 2 years, weight loss and maintenance were better for low-carb and Mediterranean-style diets as compared to low-fat diets. ...

... The low-carb diet was most beneficial for lowering triglycerides, the main fat-carrying particle in the bloodstream, and also delivered the biggest boost in protective HDL cholesterol ...

... a moderately low-carbohydrate diet can help the heart, as long as protein and fat selections come from healthy sources ...

A 20-year prospective study of 82,802 women looked at the relationship between lower carbohydrate diets and heart disease; a subsequent study looked at lower carbohydrate diets and risk of diabetes. Women who ate low-carbohydrate diets that were high in vegetable sources of fat or protein had a 30 percent lower risk of heart disease and about a 20 percent lower risk of type 2 diabetes, compared to women who ate high-carbohydrate, low-fat diets ... women who ate low-carbohydrate diets that were high in animal fats or proteins did not see any such benefits

More evidence of the heart benefits from a lower-carbohydrate approach comes from a randomized trial known as the Optimal Macronutrient Intake Trial for Heart Health (OmniHeart).  A healthy diet that replaced some carbohydrate with protein or fat did a better job of lowering blood pressure and “bad” LDL cholesterol than a healthy, higher-carbohydrate diet.

Similarly, the small “EcoAtkins” weight loss trial compared a low-fat, high-carbohydrate vegetarian diet to a low-carbohydrate vegan diet that was high in vegetable protein and fat. While weight loss was similar on the two diets, study subjects who followed the low-carbohydrate “EcoAtkins” diet saw improvements in blood lipids and blood pressure."

[Harvard School of Public Health]

Low-carb vegan diet may reduce heart disease risk, weight
May 22, 2014
"In addition to weight loss, a vegan low-carbohydrate diet may also reduce the risk of heart disease by 10 percent over 10 years"
[St. Michael's Hospital / British Medical Journal Open]

Low-carb vs. low-fat diets: Clinicians weigh in
September 1, 2014
Two articles recently published review and compare the low-carb and low-fat diets. A low-carbohydrate diet is more effective for weight loss and reducing cardiovascular risk factors than a low-fat diet, they conclude
[American College of Physicians]

Starch intake may influence risk for breast cancer recurrence, study suggests
December 23, 2011
"Researchers have linked increased starch intake to a greater risk for breast cancer recurrence, according to results presented at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium ... "The results show that it's not just overall carbohydrates, but particularly starch" ... "Women who increased their starch intake over one year were at a much likelier risk for recurring.""
[American Association for Cancer Research]

Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors
"A systematic review and meta-analysis were carried out to study the effects of low-carbohydrate diet (LCD) on weight loss and cardiovascular risk factors … A total of 23 reports, corresponding to 17 clinical investigations, were identified as meeting the pre-specified criteria. Meta-analysis carried out on data … showed the LCD to be associated with significant decreases in body weight, body mass index, abdominal circumference, systolic blood pressure, diastolic blood pressure, plasma triglycerides, fasting plasma glucose, glycated haemoglobin, plasma insulin, and plasma C-reactive protein, as well as an increase in high-density lipoprotein cholesterol … Low-density lipoprotein cholesterol and creatinine did not change significantly, whereas limited data exist concerning plasma uric acid. LCD was shown to have favourable effects on body weight and major cardiovascular risk factors; however the effects on long-term health are unknown"
[Schwingshackl L, Hoffmann G., Obes Rev. 2013 Feb; 14(2):183-4.]

Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes
March 2013
"A total of 20 RCTs were included ... The low-carbohydrate, low-GI, Mediterranean, and high-protein diets all led to a greater improvement in glycemic control ... with the largest effect size seen in the Mediterranean diet. Low-carbohydrate and Mediterranean diets led to greater weight loss ... with an increase in HDL seen in all diets except the high-protein diet"
[Am J Clin Nutr March 2013 vol. 97 no. 3 505-516]

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