Research suggest that intermittent fasting to lose weight brings several side effects such as lower blod sugars and blood pressure.

Researchers are applying the intermittent fasting to fat rats and are finding excelent results. They lose weight, their blood pressure, cholesterol, and blood sugars improve. Studies in humans, show that intermittent fasting is safe and effective, but not necessarily more effective than any other diet.

But a growing body of research suggests that the timing of the fast is key. Timing can make intermittent fasting a more realistic, sustainable, and effective approach for weight loss.

The backstory on intermittent fasting to lose weight

Using intermittent fasting to lose weight has become common practice through the ages, but three people made it popular:

  1. Dr. Michael Mosley: The BBC broadcast journalist who made the documentary Eat Fast, Live Longer and wrote The Fast Diet.
  2. Kate Harrison: The journalist who wrote the book The 5:2 Diet based on her own experience.
  3. Dr. Jason Fung: Who wrote the bestseller The Obesity Code.

After people started applying intermittent fasting, it generated a steady positive buzz as anecdotes of its effectiveness proliferated.

I recommend reading the three books I mentioned, for anyone trying to understand the causes of weight loss. Of those The Obesity Code seemed the most evidence-based summary resource, and you will love it. Fung combines plenty of research, his clinical experience, and sensible nutrition advice to explain why we get fat. He is very clear about the two things we should do to lose weight:

  1. Eat: more fruits and veggies, fiber, healthy protein, and fats, and
  2. Avoid: sugar, refined grains, processed foods, and stop snacking.

Intermittent fasting to lose weight

Intermittent fasting makes intuitive sense. Enzymes in our gut break down the food we eat and eventually it ends up as molecules in our bloodstream. Enzymes break down carbohydrates, particularly sugars and refined grains (think white flours and rice), which our cells use for energy. If our cells don’t use it all, we store it in our fat cells as, well, fat. But sugar can only enter our cells with insulin, a hormone made in the pancreas. Insulin brings sugar into the fat cells and keeps it there.

Between meals, our insulin levels go down and our fat cells release their sugar, to give energy to our bodies. We lose weight if we let our insulin levels go down. Intermittent fasting allows the insulin levels to go down long enough so that we burn off our fat.

Intermittent fasting to lose weight can be hard… but it doesn’t have to

In the past human studies that compared fasting every day and eating less showed that both worked about equally for weight loss. However people struggled with the fasting days. So I had written off intermittent fasting as no better or worse than simply eating less, only far more uncomfortable.

However new research is suggesting that not all intermittent fasting approaches are the same. Some are actually very reasonable, effective, and sustainable, when combined with a nutritious plant-based diet.

Humans have evolved to be in sync with the day/night cycle, i.e., a circadian rhythm. Our metabolism has adapted to daytime food, nighttime sleep. Research associates nighttime eating with a higher risk of obesity, as well as diabetes.

Researchers from the University of Alabama conducted a study with a small group of obese men with prediabetes. Researchers compared two forms of intermittent fasting:

  1. 8 hour period: where all meals fit into an early eight-hour period of the day (7 am to 3 pm)
  2. 12 hour period: where all meals fit into a twelve-hour period (7 am to 7 pm).

Both groups maintained their weight, but after five weeks the side effects for the eight-hours were remarcable:

  • Lower insulin levels.
  • Better insulin sensitivity.
  • Lower blood pressure.
  • Decreased appetite.

Just changing the timing of meals, by eating earlier in the day and extending the overnight fast, significantly benefited metabolism.

Is this as good as it sounds?

We receive a lot of emails from curious people asking the same question. The opinion of metabolic expert Dr. Deborah Wexler, Director of the Massachusetts General Hospital Diabetes Center and associate professor at Harvard Medical School is this:

“The circadian rhythm fasting approach, works well. But people should use an eating approach that works for them.”

Dr. Deborah Wexler

So here’s the deal. There is scientific evidence suggesting that circadian rhythm fasting, combined with a healthy diet and lifestyle, helps people to lose weight. However, people with diabetes or who are on medications for diabetes, people with a history of eating disorders like anorexia and bulimia, and pregnant or breastfeeding women should not attempt intermittent fasting unless under the close supervision of a physician who can monitor them.

Published by John Maister

John is a nutrition researcher. He reads books, blogs and scientific studies on nutrition. He stays fit by taking walks and doing the intermittent fasting diet.

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