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Sunday, August 23, 2015

Low Carb or Low Fat?

How often do we hear people say, “I am watching my carbs?” So many people think cutting back on carbs is the best way to lose some weight.  But is this true?  Should you cut back on fat calories or carb calories?  A recent study posted by WebMD looks at carbs vs fats.  Which diet burns more fat and which diet would lead to lasting weight loss?

The title of the WebMD article gives away the study findings:  Low-Carb Diets Don't Work the Way We Thought.

  • Low carb diets – do they really “melt away the fat”?  Melt away your belly fat?   One theory behind low carb diets is that eating less carbs lowers your insulin levels in your blood.  Since insulin promotes fat storage, less insulin less fat storage.  Is this true?  The newest study says “NO”
  • Study – NIH studied 19 overweight adults.   For 11 days, they lived in a special room and everything they ate was monitored.  They even captured the air they breathed to measure exactly how many calories they burned and if they were burning calories from fat, carbs or protein.
  • Baseline  – participants ate a “normal” diet of 50% carbs, 35% fat and 15% protein – their baseline diet.
  • Low Carb  – for 6 days participants ate a diet with 30% less calories, less calories from carbs – the low carb diet plan.  Fat and protein calories remained the same as the baseline diet.
  • Low Fat -  for 6 days (after a few weeks break from the low carb diet) – calories were cut from fat, with protein and carbs remaining the same.

So what diet was the best at losing fat?  Surprisingly:

“People lost more total fat on the low-fat diet than they did when they were eating the low-carb diet.” says author Kevin Hall, PhD.

Not only was this finding a surprise but just as surprising was the change in metabolism:

“And cutting fat didn’t appear to slow metabolism, while cutting carbs did.”  The study found that cutting back on carbs lead to metabolism slowing by about 100 calories a day.  Cutting back on fat, metabolism did not slow down.

So cutting carbs slows your metabolism?  Who would want to be on a low-carb diet if doing so, slows your metabolism?

The study shows your metabolism does change on a low carb diet or on a low fat diet.  A low-carb diet does lead to fat loss but not as much fat loss as not eating all the fat in the first place.
Bottom line – if you are interested in losing weight:
Cut the Fat,  Keep the Carbs


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