Tag Archives: low-fat

December 22, 2009 · 2:00 AM

Top 10 Diabetes Superfoods

The American Diabetes Association has published a list of  Top 10 Diabetes Superfoods.  They share a low glycemic index and provide key nutrients, according to the ADA.  Click the link for details.  Here they are in no particular order:

  • beans
  • dark green leafy vegetables
  • citrus fruit
  • sweet potatoes
  • berries
  • tomatoes
  • fish high in omega-3 fatty acids
  • whole grains
  • nuts
  • fat-free milk and yogurt

Regular readers here know I have no problem generally with regular or high-fat versions of dairy products.  An exception would be for people trying to lose weight while still eating lots of carbohydrates; the low- and no-fat versions could have lower calorie counts, which might help with weight management.

But compare non-fat and whole milk versions of yogurt in the USDA nutrient database.  One cup of non-fat fruit variety yogurt has 233 calories, compared to 149 calories in plain whole milk yogurt.  The “non-fat” version  reduced the fat from 8 to 2.6 g (not zero g) and replaced it with sugars (47 g versus 11 g). 

Unfortunately, your typical supermarket yogurts are low-fat yet loaded with sugar or high fructose corn syrup that impede weight loss.

Nevertheless, this superfoods list may give us some guidance in design of a Diabetic Mediterranean Diet.  Except for “fat-free,” everything else on the list is a component of the traditional healthy Mediterranean diet.  “Fat-free” is a modern invention and not necessarily an improvement.

Steve Parker, M.D.

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Filed under Dairy Products, Fish, Fruits, Glycemic Index and Load, Grains, Health Benefits, legumes, Mediterranean Diet, nuts, Vegetables

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December 18, 2009 · 4:18 PM

Low-Carb Killing Spree Continues

The choice is clear . . . NOT

Low-fat and low-carb diets produce equal weight loss and improvements in insulin resistance but the low-carb diet may be detrimental to vascular health, according to a new study in Diabetes.

Methodology

Researchers in the the UK studied 24 obese subjects—15 female and 9 male—randomized to eat either a low-fat (20% fat, 60% carbohydrate) or low-carb (20% carb, 60% fat) diet over 8 weeks.  Average age was 39; average body mass index was 33.6.  Most of them had prediabetes.  Food intake was calculated to result in a 500 calorie per day energy deficit (a reasonable reduced-calorie diet, in other words).  Study participants visited a nutritionist every other day, and all food was provided in exact weighed portions. 

Results

Both groups lost the same amount of weight, about 7.3% of initial body weight. 

Triglycerides dropped by a third in the low-carb group; unchanged in the low-fat cohort.  Changes in total cholesterol, LDL cholesterol, and HDL changes were about the same for both groups.

Systolic blood pressure dropped about 10 points in both groups; diastolic fell by 5 in both.

“Aortic augmentation index” fell significantly in the low-fat group and tended to rise in the low-carb group.  According to the researchers, the index is used to estimate systemic arterial stiffness.  [In general, flexible arteries are better for you than stiff ones.  “Hardening-of-the-arteries,” etc.]  The low-fat group started with a AAI of 17, the low-carb group started at 12.  They both ended up in the 13-14 range. 

Peripheral insulin sensitivity improved significantly only in the low-carb group but “there was no significant difference between groups.”  No difference between the groups in hepatic (liver) insulin resistance. 

Fasting insulin levels fell about 20% in the low-fat group and about 40% in the low-carb group, a difference not reaching statistical significance (p=0.17).

The Authors’ Conclusions

This study demonstrates comparable effects on insulin resistance of low-fat and low-carbohydrate diets independent of macronutrient content.  The difference in augmentation index may imply a negative effect of low-carbohydrate diets on vascular risk.

My Comments

Yes, you can indeed lose weight over eight weeks on both low-fat and low-carb diets, if you follow them.  So diets DO work.  No surprise.

Loss of excess body fat by either method lowers your blood pressure.  No surprise.

Once again, concerns about low-carb/high-fat diets adversely affecting common blood lipids—increasing heart disease risk—are not supported.  No surprise

Hyperinsulinemia and insulin resistance are risk factors for development of diabetes and cardiovascular disease.  Results here tend to favor the low-carb diet.  I have to wonder if a study with just twice the number of test subjects would have shown a clear superiority for the low-carb diet.

The authors imply that aortic augmentation index is an important measure in terms of future cardiovascular health.  A major conclusion of this study is that a change in this index with the low-carb diet might adveresly affect heart health.  Yet they don’t bother to discuss this test much at all.  I’m no genius, but neither are the typical readers of Diabetes.  I doubt that they are any more familiar with that index than am I, and I’d never heard of it before. 

[Feel free to educate me regarding aortic augmentation index in the comment section.]

Unfortunately, many readers of this journal article and the associated news releases will come away with the impression, once again, that low-carb diets are bad for your heart. 

I’m not convinced.

Steve Parker, M.D.   

References:

Bradley, Una, et al.  Low-fat versus low-carbohydrate weight reduction diets.  Effects on weight loss, insulin resistance, and cardiovascular risk: A randomized control trial.  Diabetes, 58 (2009): 2,741-2,748.

Nainggolan, Lisa.  Low-carb diets hit the headlines again.  HeartWire, December 11, 2009.

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Filed under Carbohydrate, coronary heart disease, Fat in Diet, Prevention of T2 Diabetes, Weight Loss

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August 15, 2009 · 10:33 AM

Atkins Diet Beats Low-Fat Diet Over Three Months in Overweight Diabetic Black Women

MPj04384250000[1]A recent study compared effects of a low-carb versus low-fat diet in overweight diabetics (mostly blacks).  After one year, the only major difference they found was  lower HDL cholesterol in the low-carb eaters.  The low-carb diet was more effective measured at three months into the study.  Study participants were overwhelmingly black women, so the findings may not apply to you.

Background

The authors note at the outset that:

Optimal weight loss strategies in patients with type 2 diabetes continue to be debated, and the best dietary strategy to achieve both weight loss and glycemic control . . . is unclear.

They also note that in short-term randomized studies, low-carb diets help improve glucose control in type 2 diabetics.

Methodology

Participants (105) were randomized to either:

  • a low-fat diet in the fashion of the Diabetes Prevention Program, with a fat gram goal of 25% of energy needs, or . . .
  • the Atkins diet, including the 2-week induction phase and gradually increasing carb grams weekly, etc.

The adult partipants were black (64%), Hispanic (16%), white (15%), or other.  Women were 80% of the group.  Average age 54.  Average weight 215 pounds (98 kg).  Average BMI 36.  Most of them were taking metformin, half were taking a sulfonylurea, 30% were on insulin.  Thiazolidinedione drugs were discontinued since they cause weight gain as a side effect.  Short-acting insulins were changed to glargine (Lantus) to help avoid hypoglycemia.  For the low-carb group initially, insulin dosages  were reduce by half and sulfonylureas were stopped (again, to minimize hypoglycemia).  For the low-fat group, insulin was reduced by 25% and sulfonylurea by 50%.  Metformin was not adjusted.  Subjects were instructed to keep daily food diaries.  Goal rate of weight loss was one pound per week.   

Results

The drop-out rate by the end of 12 months was the same in both groups – 20%.  The low-carbers lost weight faster (3.7 lb/month) in the first three months, but by month twelve each group had the same 3.4% reduction of weight (6.8 lb or 3 kg).  As measured at 3 months, low-carbers were down 11.4 lb (5.2 kg) and low-fat dieters were down 7 lb (3.2 kg).  Maximum weight loss was at 3 months, then they started gaining it back.  At 12 months, low-carb subjects using insulin were on 10 less units, while low-fat dieters were using 4 more units (not statistically significant).  Hemoglobin A1c measured at 3 months was down 0.64 in the low-carb group and down0.26 in the low-fat.  By 12 months, HgbA1c’s were back up to baseline levels for both groups.  Blood lipids were the same for both groups at 12 months except HDL was about 12% higher in the low-carb dieters.

At baseline, subjects derived 43% of calories from carbohydrates, 36% from fats, 23% from proteins.  At three months, the low-carb group ate 24% of calories as carbohydrates (estimated at 77 grams of carb daily) and 49% from fat.  The low-fat group at 3 months derived 53% of calories from carbohydrate (199 grams/day) and 25% from fat. Diet compliance deteriorated as time passed thereafter. 

Study Author Conclusions

After one year, the low-carb and low-fat groups had similar weight reductions.  The low-carb dieters raised their HDL cholesterol levels significantly [which may protect against heart disease].

My Comments

Lasting weight loss is difficult!  Down only 6.8 pounds for a year of  effort. 

These study participants needed to lose a lot more than 6.8 pounds.  They needed to lose 50.  Both groups were woefully noncompliant with diet recommendations by the end of the study year.  They were eating more carbs or other calories than they were assigned.  But their results weren’t much different than other groups studied for an entire year. 

How do we keep people fired up about maintaining their weight-loss efforts?  The solution to that problem will win someone a Nobel Prize.

The Atkins diet was superior – for weight loss and glycemic control – when measured at three months, when compliance by both groups was still probably fairly good.

Results of this study may apply only to black women.  There weren’t enough men and other ethnic groups to make meaningful comparisons.    

Steve Parker, M.D.        

Reference:  Davis, Nichola, et al.  Comparative study of the effects of a 1-year dietary intervention of a low-carbohydrate diet versus a low-fat diet on weight and glycemic control in type 2 diabetes.  Diabetes Care, 32 (2009): 1,147-1,152.

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