Tag Archives: low-carbohydrate diet

August 18, 2015 · 4:37 AM

New Study Suggests Low-Carb Diet Healthier Than Low-Fat in T2 Diabetes

This is an important report because most diet studies last much less than one year. Details are in the American Journal of Clinical Nutrition.

Study participants were 115 obese (BMI 35) type 2 diabetics with hemoglobin A1c averaging 7.3%. Average age was 58. So pretty typical patients, although perhaps better controlled than average.

They were randomized to follow for 52 weeks either a very low-carbohydrate or a high-carbohydrate “low-fat” diet. Both diets were designed to by hypocaloric, meaning that they provided fewer calories than the patients were eating at baseline, presumably with a goal of weight loss. The article abstract implies the diets overall each provided the same number of calories. They probably adjusted the calories for each patient individually. (I haven’t seen the full text of the article.) Participants were also enrolled in a serious exercise program: 60 minutes of aerobic and resistance training thrice weekly.

Kayaking is an aerobic exercise if done seriously

Kayaking is an aerobic exercise if done seriously

The very low-carb diet (LC diet) provided 14% of total calories as carbohydrate (under 50 grams/day). The high-carb diet (HC diet) provided 53% of total calories as carbohydrate and 30% of calories as fat. The typical Western diet has about 35% of calories from fat.

Both groups lost weight, about 10 kg (22 lb) on average. Hemoglobin A1c, a reflection of glucose control over the previous three months, dropped about 1% (absolute reduction) in both groups.

Compared to the HC diet group, the LC dieters were able to reduce more diabetes medications, lower their triglycerides more, and increase their HDL cholesterol (“good cholesterol”). These triglyceride and HDL changes would tend to protect against heart disease.

SO WHAT?

You can lose weight and improve blood sugar control with reduced-calorie diets—whether very low-carb or high-carb—combined with an exercise program. No surprise there.

I’m surprised that the low-carb group didn’t lose more weight. I suspect after two months of dieting, the low-carbers started drifting back to their usual diet which likely was similar to the high-carb diet. Numerous studies show superior weight loss with low-carb eating, but those studies are usually 12 weeks or less in duration.

The low-carb diet improved improved lipid levels that might reduce risk of future heart disease, and allowed reduction of diabetes drug use. Given that we don’t know the long-term side effects of many of our drugs, that’s good.

If I have a chance to review the full text of the paper, I’ll report back here.

Steve Parker, M.D.

Reference: Jeannie Tay, et al. Comparison of low- and high-carbohydrate diets for type 2 diabetes management: a randomized trial. First published July 29, 2015, doi: 10.3945/​ajcn.115.112581    Am J Clin Nutr

3 Comments

Filed under Carbohydrate, Heart Disease, Weight Loss

Tagged as , , , , ,

September 27, 2013 · 5:06 AM

Do Clinical Studies Support Carbohydrate-Restricted Eating in Type 1 Diabetes?

Sweden has lots of blondes

Sweden has lots of blondes

Yes, there are a few. We’ll take a close look at one today. (See the references below for more.)

In the introduction to the study at hand, the authors note:

The estimation of the amount of carbohydrates in a meal has an error rate of 50%. The insulin absorption may vary by up to 30%. It is therefor virtually impossible to match carbohydrates and insulin which leads to unpredictable blood glucose levels after meals. By reducing the carbohydrates and insulin doses the size of the blood glucose fluctuations can be minimized. The risk of hypoglycemia is therefore minimized as well. Around-the-clock euglycemia [normal blood sugar] was seen with 40 g carbohydrates in a group of people with type 1 diabetes [reference #2 below].

The immediate resulting stable, near-normal blood glucose levels allow individuals to predict after-meal glucose levels with great accuracy.

For individuals with type 1 diabetes one year audit/evaluation of group education in this regimen has shown that the short-time lowering of mean hemoglobin A1c by 1 percentage unit and the reduction in mean rate of symptomatic hypoglycemia by 82% was maintained [reference #3].

***

There is no evidence for the use of the widely recommended high-carbohydrate, low-fat diet in type 1 diabetes.

Study Set-Up

Swedish investigators educated study participants on carbohydrate-restricted eating from 2004 to 2006 [reference #1]. They recently audited their medical records for results accumulated over four years. At the outset, participants were given 24 hours of instruction over four weeks. My sense is that they all attended the same diabetes clinic. The subjects’ mean age was 52 years and they had diabetes for an average of 24 years. Seven had gastroparesis. Fourteen used insulin pumps. Of the 48 study subjects, 31 were women, 17 were men. The diet regimen restricted carbohydrates to a maximum of 75 grams a day, mainly by reducing starchy food.

Results

As measured three months after starting the diet, HDL-cholesterol rose and triglycerides fell to a clinically significant degree (p<0.05). Average weight fell by 2.7 kg (a little over a pound); average baseline weight was 77.6 kg (171 lb). Hemoglobin A1c fell from 7.6 to 6.3% (Mono-S method).

As measured one year after start, meal-time insulin (rapid-acting, I assume) fell from 23 to 13 units per day. Long-acting insulin was little changed at around 19 units daily.

By two years into the study, half the participants had stopped adhering to the diet. The remainder were adherent (13 folks) or partly adherent (10). We don’t know what the non-adherents were eating.

Four years out, the adherent group had hemoglobin A1c of 6.0%, and the partly adherents were at 6.9% (p<0.001 for both). The non-adherent group had returned to their baseline HgbA1c (7.5%). Remember, at baseline the average HgbA1c for the group was 7.6%.

The authors don’t say how many participants were still adherent after four years. From Figure 2, adherence seems to have been assessed at 60 months: 8 of the 13 adherent folks were still adherent, and 5 of the 10 partly adherent were still in the game. So, of 48 initial subjects, only 13 were still low-carbing after five years later. By five years out, half of all subjects seem to have been lost to follow-up. So the drop-out rate for low-carbers isn’t as bad as it looks at first blush.

Conclusion

The authors write:

An educational program involving a low-carbohydrate diet and correspondingly reduced insulin doses for informed individuals with type 1 diabetes gives acceptable adherence after 4 years. One in two people attending the education achieves a long-term significant HbA1c reduction.

They estimate that this low-carb diet “may be an option for 10-20% of the patients with type 1 diabetes.” Only 17% of their current diabetes clinic population is interested in this low-carb diet. They didn’t discuss why patients abandon the diet or aren’t interested in the first place. Use your imagination.

Major carbohydrate restriction in type 1 diabetics significantly improves blood sugar control (decreases HgbA1c), lowers insulin requirements, and improves cardiovascular disease risk factors (increases HDL cholesterol and lowers triglycerides).

Low-carb eating wasn’t very appealing to Swedes in the mid-2000s. I wonder if it’s more popular now with the popularity of LCHF dieting (low-carb, high-fat) in the general population there.

Steve Parker, M.D.

References:

1.  Nielson, J.V., Gando, C., Joensson, E., and Paulsson, C. Low carbohydrate diet in type 1 diabetes, long-term improvement and adherence: A clinical audit. Diabetology & Metabolic Syndrome, 2012, 4:23. http://www.dmsjournal.com/content/4/1/23

2.  O’Neill, D.F., Westman, E.C., and Bernstein, R.K. The effects of a low-carbohydrate regimen on glycemic control and serum lipids in diabetes mellitus. Metabolic Syndrome and Related Disorders, 2003, 1(4): 291-298.

3.  Nielsen, J.V., Jönsson, E. and Ivarsson, I. A low carbohydrate diet in type 1 diabetes: clinical experience – A brief report. Upsala Journal of Medical Sciences, 2005, 110(3): 267-273.

1 Comment

Filed under Carbohydrate

Tagged as , , , ,

November 20, 2009 · 2:00 AM

For Heart’s Sake, Should You Avoid Red Meat in a Low-Carb Diet?

Low carbohydrate diets tend to contain disproportionate amounts of fat from animal sources.  Red meat has long been vilified as a major source of saturated fat that some experts believe cause hardening-of-the-arteries (atherosclerosis) via elevations in LDL cholesterol.  Others disagree.  Poultry, fish ,and shellfish generally have lower amounts of saturated fat than red meat.  Would a low-carb diet with a predominance of poultry, fish, and shellfish lead to a more advantageous cholesterol profile?

A 2007 report from U.S. researchers found no lipid advantage to the poultry/fish/shellfish model.    In fact, despite high cholesterol and fat intakes, neither diet caused a significant change in total, HDL, or LDL cholesterol levels.  Triglycerides fell in both groups, but to a statistically significant degree only on the poultry/fish/shellfish group.

Fun Fact:  Did you know that four of every 10 women in the U.S. are trying to lose weight?  The figure for men is one in three.  

Methodology

Researchers in Minnesota and Iowa enrolled 18 subjects (6 males, 12 females) between the ages of 30 and 50 who wanted to lose weight.  Average body mass index was 31.7, which is mildly obese.  The were encouraged to eat an Atkins-style ketogenic diet with a maximum of 20 g carbs/day, providing 1,487 total daily calories, with 7% of calories from carbohydrate, 43% from protein, and 50% from fat.  This included two or three cups of salad greens and low-carb vegetables.  Three ounces of cheese daily was allowed.  Subjects were randomly assigned to eat either red meat or poultry/fish/shellfish.  Dietary intervention lasted 28 days.

[This is very similar to Atkins Induction Phase, although Atkins does not limit total calories.  The researchers did not say why they wanted to limit total calories.] 

Data were not used from six subjects for good reasons (see article).  So final data analysis included only 12 subjects.

Results

Both groups lost the same amount of weight: about 5.5 kg (12 pounds) over 28 days.

Average carbohydrate intake was about the same for both groups: 55 g/day.

Average total daily caloric intake was about the same for both groups: 1,380.

The poultry/fish/shellfish group ate 630 mg cholesterol daily, twice as much as the other group.  [Eggs and shrimp were popular.]

The difference in intake of saturated fat approached, but did not reach, statistical significance (32 g/day in the red meat group vs 25 g).

Neither diet caused a significant change in total, HDL, or LDL cholesterol levels.  Triglycerides fell in both groups, but to a statistically significant degree only on the poultry/fish/shellfish group.

Urine ketones at or above 5 mg/dl were detected on 75% of all dipstick tests.

My Comments

I’m skeptical about the accuracy of the calorie counts.  Most people eating Atkins-style take in about 1,800 cals/day.  The preponderance of females, however, may explain the unusually low average caloric intake.  They didn’t follow their carb restriction very closely, did they?  These were free-living subjects not locked in a metabolic ward.

The researchers note that the allowance of cheese in both groups may have sabotaged their efforts for a clear delineation of higher versus lower saturated fat groups. 

HDL cholesterol usually rises significantly on low-carb diets.  Lack of that here may just be a statistical aberration.

This is such a small study that it’s impossible to draw firm conclusions.  Nevertheless, if someone is losing weight on a low-carb diet, it may not matter much from a lipid viewpoint whether they eat a predominance of meat or a predominance of poultry, fish, and shellfish.  The study at hand cannot address the long-term consequences of such a choice.

Steve Parker, M.D.

Reference:  Cassady, Bridget, et al.  Effects of low carbohydrate diets high in red meats or poultry, fish and shellfish on plasma lipids and weight loss.  Nutrition & Metabolism, 4:23   doi: 10.1186/1743-7075-4-23   Published October 31, 2007

Comments Off on For Heart’s Sake, Should You Avoid Red Meat in a Low-Carb Diet?

Filed under Carbohydrate, Fish, ketogenic diet, Overweight and Obesity

Tagged as , , , , , , ,

July 5, 2009 · 2:00 AM

ADA Now Says Low-Carb Diets OK for Overweight Type 2 Diabetics

CB037166Eighty-five percent of type 2 diabetics are overweight or obese.  Overweight either causes or aggravates many cases of diabetes.

For the last quarter-century, many U.S. government agencies and healthcare organizations have advocated a low-fat diet for overweight people, including type 2 diabetics.  Recent studies have documented that low-carbohydrate diets can also be effective in weight loss.  Low-carb diets replace carbohydrates with either fats or proteins, or both.  The A to Z Weight Loss Study compared the Atkins, Ornish, LEARN, and Zone diets in 311 overweight pre-menopausal women.  The Atkins group tended to lose a bit more weight. Changes in lipid profiles, waist-hip ratios, fasting insulin and glucose levels, blood pressure, and percentage of body fat were comparable or better with Atkins versus the other diets.

The Amerian Diabetes Association now gives the go-ahead for use of low-carb diets as a weight-control method for type 2 diabetics.  Previously, the organization had recommended against diets that restrict carbohydrates to less than 130 grams daily.  (A baked potatoe without the skin has 30 grams.)  Understand that the ADA does not endorse low-carb diets for weight loss or diabetes management.  They simply say that either low-carb or low-fat calorie-restricted diets might be effective for up to one year.

I caution you that low-carb diets may be deficient in fiber, minerals, vitamins, and phytonutrients that may be very beneficial in terms of long-term health and longevity.

The tide has been turning against low-fat diets for the last six years.

Steve Parker, M.D.

Reference: American Diabetes Association.  Clinical Practice Recommendations 2008.  Diabetes Care, 31 (2008): S61-S78.

2 Comments

Filed under Carbohydrate, Overweight and Obesity

Tagged as , , , , , , , , ,

June 20, 2009 · 2:00 AM

Low-Carb Diet Beats Low-Fat, Calorie-Restricted Diet

Body mass index 38

Body mass index 38

I found one of the early studies (2003) demonstrating the effectiveness and safety of an Atkins-style diet in the severely obese.  Doctors traditionally have been hesitant to recommend the Atkins diet out of concern for tolerability and potential increased atherosclerosis complication such as heart attacks, strokes, and poor circulation.

Methodology

The study enrolled 132 subjects with an average body mass index of 43, including 77 blacks and 23 women.  39% had diabetes, 43% had metabolic syndrome.  They were randomly assigned to either . . .

  1. a low-carb diet without caloric restriction (carbohydrates limited to 30 gm/day; vegetables and fruits with high ratios of fiber to carbohydrate were recommended), or
  2. a low-fat, calorie-restricted diet. 

Subjects followed their diets for six months.  The researchers never specified, but I’m assuming the diabetics were all type 2. 

Results

The drop-out rate was equally high in both groups: only 79 subjects completed the study.  The low-carb group lost 5.8 kg (13 lb); the low-fat group lost 1.9 kg (4 lb).  Analysis included the drop-outs, for reasons unclear to me.  White subjects lost more weight than blacks: 13 versus 5 kg (29 versus 11 lb).  Total cholesterol, HDL cholesterol, and LDL cholesterol levels did not change significantly within or between groups.  [HDL usually rises on a low-carb diet.]   Triglycerides fell 20% in the low-carb group and 4% in the other group.  For subjects with diabetes, glucose levels fell 26 mg/dl in the low-carb group compared to 5 mg/dl in the low-fat group.  Uric acid levels didn’t change in either group.  [Elevated uric acid levels can cause gout.]  No significant adverse reactions attibutable to the diets were recorded in either group.  Glycosylated hemoglobin fell from 7.8 to 7.2% in the low-carb group, with no change in the low-fat group.   

Take-Home Points  

It’s a small study, so results may not be very accurate or generalizable to other populations.

In this cohort with a high prevalence of diabetes, the low-carb diet was more effective than the low-fat/calorie-restricted diet for weight loss, with no adverse lipid changes to suggest increased long-term cardiovascular risk.  The low-carb diet helped control diabetes. 

Steve Parker, M.D. 

Reference:  Samaha, Frederick, et al.  A low-carbohydrate as compared with a low-fat diet in severe obesity.  New England Journal of Medicine, 348 (2003): 2,074-2,081.

2 Comments

Filed under Carbohydrate, Overweight and Obesity, Weight Loss

Tagged as , , , , , ,