New Study Compares Low-Calorie Diet with Timing of CarbohydratesBy Jarret Morrow MD on December 30, 2011@jarretmorrow
For those who’re looking to lose weight, a new study sheds some light on the best time to consume carbohydrates if you’re looking to shed some pounds. Just recently published in the journal, Obesity, the researchers compared two identical low-calorie diets on weight loss . The only difference between the experimental and control groups was the timing of their carbohydrate intake.
In total, 78 police officers with BMI’s over 30 were randomly assigned to two identical low-calorie diets. In the experimental group, they consumed carbohydrates mostly at dinner while in the control group, they consumed carbohydrates throughout the day. Both groups followed their respective diets for a duration of six months.
Again, both groups followed the same standard low-calorie diet consisting of (20% protein, 30–35% fat, 45–50% carbohydrates, 1,300–1,500 kcal) per day with the only difference being the timing of their carbohydrate intake.
In terms of the rationale behind this study, it has to do with the hormone, leptin, Leptin is a hormone that regulates satiety and it has an established diurnal variation. For example, leptin secretion falls during the day from 0800 to 1600hrs. It then increases from 1600 hrs reaching a zenith at 0100. In effect, leptin which is known as “the satiety hormone) peaks while you’re sleeping.
Another key hormone in obesity research is adiponectin. Adiponectin reduces inflammation, insulin resistance, and lowers serum carbohydrate and lipid levels. It’s hypothesized to be the link between obesity, insulin resistance, and metabolic syndrome since adiponectin levels are lower throughout the day in those with abdominal obesity.
Previous studies on Muslim populations during Ramadan where they fast during the day and consume an enriched carbohydrate dinner have demonstrated that the diurnal variation of leptin can be modified.
The researchers hypothesized that the experimental diet would lead to higher leptin concentrations in the morning and throughout the day which would enhance satiety during the daytime and improve diet adherence.
What Did the Researchers Find?
- The experimental group achieved greater weight reduction as well as reductions in body fat mass and abdominal circumference.
- Hunger scores were lower in the experimental group.
- The experimental group had greater improvements in fasting glucose and average daily insulin concentrations
- Greater improvements in total cholesterol, LDL cholesterol, and HDL cholesterol were observed in the experimental group
- Markers of inflammation including tumor necrosis factor-α, IL-6, and c-reactive protein were reduced more in the experimental group
- The experimental diet modified daily leptin and adiponectin concentrations compared to baseline and the control diet
The Researchers Concluded:
Overall, we have demonstrated improvement in hunger/satiety status, persistence in the weight loss process, better anthropometric outcomes, improved insulin sensitivity, improvement in metabolic syndrome parameters, less inflammation and hormonal changes, following simple carbohydrate manipulation. Our results provide a scientific basis for proposing possible dietary alternatives that may be beneficial for people suffering from obesity, insulin resistance, and the metabolic syndrome and experiencing difficulties in maintaining a weight loss diet over the long term.
- Sofer S, Eliraz A, Kaplan S, Voet H, Fink G, Kima T, Madar Z. Greater Weight Loss and Hormonal Changes After 6 Months Diet With Carbohydrates Eaten Mostly at Dinner. Obesity (Silver Spring). 2011 Apr 7.
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