Twenty-one Day "Daniel Fast" Reduces Insulin Levels by 23%

Also improves multiple metabolic markers

The Biblical book of Daniel includes a description of what some assert to be the first dietary clinical trial recorded in "Western" literature.  In Daniel 1:8-16 (NIV) we find:

"But Daniel resolved not to defile himself with the royal food and wine, and he asked the chief official for permission not to defile himself this way. Now God had caused the official to show favor and sympathy to Daniel, but the official told Daniel, 'I am afraid of my lord the king, who has assigned your food and drink. Why should he see you looking worse than the other young men your age? The king would then have my head because of you.' Daniel then said to the guard whom the chief official had appointed over Daniel, Hananiah, Mishael and Azariah, 'Please test your servants for ten days: Give us nothing but vegetables to eat and water to drink. Then compare our appearance with that of the young men who eat the royal food, and treat your servants in accordance with what you see.' So he agreed to this and tested them for ten days. At the end of the ten days they looked healthier and better nourished than any of the young men who ate the royal food.  So the guard took away their choice food and the wine they were to drink and gave them vegetables instead. "

Daniel 10:2-3 provides a similar passage:

"At that time I, Daniel, mourned for three weeks. I ate no choice food; no meat or wine touched my lips; and I used no lotions at all until the three weeks were over." 

I wonder if these passages might provide some cognitive dissonance for Judeao-Christian followers of low-carbohydrate diets, at least those who take the Bible as guidance from God.

Whether your consider these passages history or fiction, it seems likely to me that the author(s) had some experience that informed it.  The author(s) evidently believed that 'royal food' including meat and wine pollutes and corrupts humans, and that a 10-21 day diet consisting exclusively of "vegetables" would make a person look "healthier and better nourished" than a royal diet, although at that time the meat would have come from grass-finished animals and the wine from 'organically grown' fruits.

Susan Gregory has written a book about the Daniel Fast, so-called because the follower abstains from animal foods and alcohol, while having ad libitum intake of unrefined plant foods.  The book apparently focuses on the 'fast' as a religious, not health care, method.   I myself would not call a eating plan that allows you to eat unlimited plant foods a 'fast.'  To me, doing so sort of implies that you believe that only animal products, not plants, qualify as food.  So I prefer to call this the Daniel Diet.

However, Bloomer et al decided to find out how 21 days on the Daniel Diet affects human health.

They enrolled 43 subjects ranging in age from 20 to 62, six of whom reported adhering to a 'vegetarian' diet before doing the 'fast.'  Bloomer et al give more details:

"Forty-four subjects (13 men; 31 women) were initially recruited to participate and were enrolled in this study. The mean age of subjects was 35 ± 1 years, with a range of 20-62 years. One female subject had a diagnosis of well-controlled type II diabetes (and used oral hypoglycemic agents), and one male subject had a history of coronary artery bypass graft surgery (and used both a statin and Plavix®). Three subjects were hypertensive upon enrollment (BP≥140/90 mmHg; 2 men and 1woman) and seven had hypercholesterolemia (total cholesterol > 200 mg·dL-1; 1 man and 6 women). One man used a beta blocker and one man used an anti-depressant. Three women used anti-depressants, six used oral contraceptives, two used estrogen replacement, two used a sleep aid, one used a statin, and one used an angiotensin II receptor antagonist."

Bloomer et al describe the 'fast' here:

"A Daniel Fast involves ad libitum intake of specific foods, but the food choices are restricted to essentially fruits, vegetables, whole grains, nuts, seeds, and oil. This plan resembles a vegan diet, which has been reported to yield health enhancing properties [16,17]. However, a Daniel Fast is more stringent, in that aside from the exclusion of all animal products, there are no processed foods, white flour products, preservatives, additives, sweeteners, flavorings, caffeine, or alcohol allowed in this plan."

Apparently the subjects liked the intervention:

"Subjects noted that they enjoyed the ad libitum nature of the plan, as well as the wide variety of food choices. In fact, most subjects reported that they would continue implementing many components of the plan into their previous diets."

The following table shows the dietary data of the subjects during the final 7 days of the Daniel 'fast.'

Some notes on the nutritional profile of the 'fast':

• Total protein intake declined by about one-third, but the average remained at the level recommended for a lean 77 kg/171 pound man.
• Total carbohydrate intake declined by only about 20 g per day, but as a percentage of calories, total carbohydrate intake increased from 53% to 62%.
• Fiber intake increased by more than 50% (up 14 g per day)
• Fat intake declined by 20 g per day, and from 30% of energy to 27% of energy
• Saturated fat intake declined from 24 g per day to 9 g per day, a reduction of 63%.
• Polyunsaturated fat intake increased by only 1 g.
• Omega 3 intake increased by 87 mg (12%) daily.
• Vitamin C intake increased by about 50 mg daily, but remained at only about 120 mg daily, indicating a rather low intake of vegetables and fruits by my standards.  A produce-dominated diet can easily supply 400+ mg of vitamin C daily, so this diet probably was dominated by grains, legumes, nuts, and seeds low in vitamin C.
• Vitamin E intake increased by almost 50%.

 The following three tables show some of the changes that occurred over 21 days on the Daniel Fast:

Notable improvements in table 1 include decreases in heart rate, blood pressure, body weight, and body fat.  This study did not find a marked average decline in body weight and body fat mass primarily because almost half (21) of the subjects were classified as normal weight at the outset of the study; these lean people didn't lose weight, so they diluted the weight loss average.  

Fat free mass declined by an average of 1.7 kg, which could have been water or muscle; we can't determine which from this data in table 1 alone.  However, since blood pressure and insulin levels (data below) dropped significantly, I would expect that this lean mass loss consisted primarily of a significant loss of sodium and water in the 10 overweight and 13 obese subjects in the study (because insulin increases sodium retention, hence water retention and blood pressure).

The subjects did report a small decline in mental health.  According to Bloomer et al, "Through completion of a post fast questionnaire, subjects reported that the main enervation of their mental health was the omission of caffeine."  In other words, they had caffeine withdrawal syndrome.

Notable improvements listed in table 3 include:

• Reduced blood sugar
• Reduce Blood Urea Nitrogen
• Slightly reduced AST and ALT, possibly indicating healthier liver function

 Notable improvements:

• Total cholesterol declined about 30 points to less than 150 mg/dL, a level thought to confer virtual immunity to heart attack and found by Esselstyn to allow reversal of atherosclerosis.
• Triglycerides declined by about 12%.
• LDL-C declined to about 76 mg/dL, a level found in wild animals, hunter-gatherers, and newborn infants.

In addition:

"Insulin (pre: 4.42 ± 0.52 vs. post: 3.37 ± 0.35 μU·mL-1; p = 0.10), HOMA-IR (pre: 0.97 ± 0.13 vs. post: 0.72 ± 0.08; p = 0.10), and CRP (pre: 3.15 ± 0.91 vs. post: 1.60 ± 0.42 mg·L-1; p = 0.13) were lowered in a clinically meaningful manner, although this decline failed to reach statistical significance."

This whole foods diet rich in carbohydrates produced a 23% decline in insulin levels, a 26% decline in insulin resistance (measured by HOMA-IR),  and a 49% decline in C-reactive protein, indicating a substantial decline in inflammation.  Although not statistically significant, these are clinically very significant reductions boding well for these subjects.

Did the Daniel Diet affect obese people differently from lean?  Apparently not.

"Although our intention with this study was not to make comparisons between normal weight and overweight/obese subjects, in an attempt to clarify our findings we also analyzed data using a 2 (weight status: normal weight vs. overweight/obese) × 2 (pre/post fast) analysis of variance. No interaction effects were noted for any variable (p > 0.05), indicating that normal weight and overweight/obese subjects respond to the Daniel Fast in a similar manner."

Although not inspired by the Bible, Tracy and I have been eating mostly (well more than 99%) plant foods for a couple of months now, as an ongoing experiment.  We differ from the Daniel Fast in that we have emphasized eating more like a wild chimp or gorilla: lots of green leaves, non-green vegetables (including starchy vegetables), fruits, beans, nuts, and seeds, while limiting whole grains, not including them every day or in large amounts. 

Compared to my previous experiments with diets containing minimal or no animal products, I have recently focused on eating larger amounts of green and starchy vegetables, nuts, and seeds, with limited amounts of beans, even more limited whole grains.  In those past experiments I ate very limited amounts of nuts and seeds but large amounts (2-3 times daily) of whole grains including substantial amounts of home-made whole wheat breads (both sourdough and yeasted) on most days. Now I have many days with no grains at all, and very little wheat in comparison.

We have so far responded very favorably to this produce-dominated, 99%+ plant food approach.  We'll see how it progresses.