The idea for the Daniel Plan was conceived in November, 2010, after a pastor named Rick Warren baptized over 800 people by immersion in one day. Lowering so many people into the water caused Warren to realize that everyone was overweight, including himself. He decided to do something about it.
Warren consulted with three high-profile doctors who are also best-selling authors (Mehmet Oz, Daniel Amen and Mark Hyman) and enlisted their help in developing a diet and exercise plan. Once the strategy was complete, Warren invited his congregation (over 22,000 members) to join him in the effort to lose weight, exercise more, and get healthier. Twelve thousand people signed up initially to participate. 
HOW THE PLAN WAS NAMED
Warren said, "We just took the title [The Daniel Plan] from that concept [Daniel's request to eat only vegetables and water in the first chapter of Daniel]. It [the plan] doesn't try to follow what Daniel ate, because the Bible doesn't tell us exactly what he ate." 
The prophet Daniel comes to our attention initially in the Old Testament, in the first chapter of the book of Daniel. Around 605 B.B., King Nebuchadnezzar of Babylon besieged Jerusalem and captured it:
The king ordered Ashpenaz, chief of his court officials, to bring in some of the Israelites from the royal family and the nobility—young men without any physical defect, handsome, showing aptitude for every kind of learning, well informed, quick to understand, and qualified to serve in the king's palace. He was to teach them the language and literature of the Babylonians. The king assigned them a daily amount of food and wine from the king's table. They were to be trained for three years, and after that they were to enter the king's service. (Daniel 1:3-5)
It's not clear how many young Israelite men (many of them teenagers) were captured altogether, but the young prophet Daniel and three of his friends — Hananiah, Mishael and Azariah — were among them (Daniel 1:6).
As devout Jews, Daniel and his friends followed Mosaic Law and did not eat anything the Law defined as "unclean." Once Daniel learned that he was to be given a daily allotment of unclean food and wine from the King's table, he became determined not to defile himself by partaking of it (Daniel 1:8).
Daniel diplomatically requested permission from the commander of the officials to eat only "pulses" (KJV rendering; other translations say "vegetables") and drink only water for ten days. "Then let our appearance be observed in your presence and the appearance of the youths who are eating the king's choice food; and deal with your servants according to what you see" (Daniel 1:13).
The commander agreed, and in ten days' time, Daniel and his friends looked much healthier than all of the youths who ate and drank the food and wine from the King's table. The four young men had even gained weight, so they were permitted to continue eating pulses and drinking water (Daniel 1:15-16).
THE PROPHET DANIEL'S PLAN
Daniel objected to eating the King's meat and wine primarily for religious, spiritual and moral reasons (Daniel 1:8; Leviticus 11:4-20). The Old Testament warns that a person should prefer to cut his own throat rather than being desirous of a ruler's "dainties" and "deceitful meat" (Proverbs 23:1-3). Daniel trusted God to keep him and his friends healthy in spite of a limited diet, because they refused to break faith with Him in spite of being under extreme pressure to do so. "...however wholesome, [pulses were] not naturally calculated to render them [Daniel and his peers] fatter in flesh than the others." 
What made the king's food and drink unclean? Consider pork, which was a favorite of the Babylonians, even though it is common for pigs to eat their own feces (a phenomenon called coprophagia). In those days, meat was typically eaten either raw or undercooked. Pork is one meat in particular that should be thoroughly cooked because of the high degree of bacterial and parasitic contamination. God protected the Jews by forbidding them from consuming the flesh of swine (Leviticus 11:7-8). 
Old Testament dietary laws also forbade indulging in intoxicating wine (Proverbs 23:31-35). Drinking wine mixed with blood was even worse — an abomination to God — but it was a practice the Babylonians were well known for (Genesis 9:4; Leviticus 3:17).
Additionally, meat from the palace would also most likely have been dedicated to idols, before being served to King Nebuchadnezzar and his court. Daniel may have either witnessed this practice or suspected it was going on, since he was as well educated as he was pious.
It is interesting to note that the barbaric Babylonians were sophisticated in at least one area: cooking. Eating their rich, perhaps spicy food might have upset Daniel's stomach, since he would have been used to simpler, kosher fare. However, this would have been low on Daniel's priorities list. Instead, he surely recognized that by eating the king's food and drink, others would see it as a sign of his acceptance and approval of pagan beliefs and practices.
DANIEL'S DIET: "PULSES" AND WATER
Pulses (Daniel 1:12, KJV) may be defined as follows: "...an edible seed that grows in a pod...all beans, peas and lentils..." 
Pulses have also been described as all leguminous plants which have been pulled or plucked, but not reaped. Under certain circumstances, this could include grains such as corn, wheat or barley. For example, Mosaic Law permitted one to eat fresh, raw grain from a neighbor's field by rolling the ears in the hands to free the grain from the husks, but it could not be harvested with a sickle (Deuteronomy 23:25; Matthew 12:1).
There is some argument as to whether or not pulses consist of only the seed or bean portion of a plant, or the entire plant. Certain fruits (such as dates), roots, and leaves are sometimes considered to be pulses.
Daniel's request for pulses would not have been unusual for the young Hebrew. A typical Jewish household's daily diet was almost exclusively vegetarian. Meat was usually only served on special occasions (such as a wedding). We can't know exactly what Daniel ate since some varieties of pulses that were available then would not be obtainable now, and vice-versa.
NUTRITIONAL VALUE OF PULSES
Pulses contain a high percentage of easily digestible protein by weight; as much as 20-25%. Except for low levels of methionine (an essential amino acid), the quality of pulse protein is fairly high. Pulses have twice as much protein as wheat and three times as much as rice. 
Grains can be combined with leguminous plants to form complete proteins if you know which ones to mix together. A meal that is complete in protein will contain all 20-21 basic dietary amino acids. Nine to ten of them are considered essential and ten to eleven others are regarded as non-essential. Pulses also provide complex carbohydrates and several vitamins and minerals, including iron, magnesium, phosphorous, zinc, and other minerals. Pulses have no cholesterol, and are low in fat and sodium and high in fiber. 
Sesame seeds, which are high in methionine, can be used to complete the protein in pulses. Corn is high in lysine, another essential amino acid that is typically found only at low levels in other grains.
Daniel wisely asked for pulses and water alone because controlling his diet in this manner ensured he would avoid all wine, unclean meat and anything non-kosher or dedicated to idols. He would then be protected from disobeying the religious, moral and dietary laws that God had given Moses at Sinai (Leviticus 11; Deuteronomy 14).
HOW DOES THE DANIEL PLAN DIET COMPARE TO THE BIBLICAL DANIEL'S DIET?
Daniel's motive was simply not to compromise his beliefs, break God's laws, or dishonor Him. The Daniel Plan was established to help Warren and others lose weight, exercise regularly, support each other, and become healthier. 
While the biblical Daniel limited himself to pulses and water, The Daniel Plan encourages eating a much wider variety of foods. Each meal is divided up in the following manner: 25% protein (animal or vegetable); 25% whole grains or healthy starches; 50% non-starchy vegetables; a side of low-glycemic fruit (depending on the need to limit sugar); herbal teas, and water.
The Daniel Plan also encourages the use of certain spices and super foods that have been credited with having healing properties, as well as high-quality vitamin and mineral supplements. You can find a list of all recommended foods online; it can be adapted for anyone who prefers to follow a vegan or vegetarian diet. [9, 10]
FIVE COMPONENTS FOR WELLNESS
The Daniel Plan is also a lifestyle program with five essential components: food, fitness, focus, faith and friends. Warren says, "The program incorporates healthy eating, regular exercise, stress reduction, prayer and support from other church members in small home groups." 
SHOULD A CHRISTIAN FOLLOW THE DANIEL PLAN DIET?
Are the foods allowed on the Daniel Plan diet healthy foods? Yes. Is the Daniel Plan diet biblical? No — and therein lies the rub.
Christians should not be surprised at the instant appeal a title like The Daniel Plan
might offer them. We all hold the biblical Daniel in high regard and want to have the integrity and faithfulness that he had. One may infer from the title alone that if she goes on the Daniel Plan, she will be emulating the biblical Daniel. I don't know about you, but it bothers me to see a diet plan being called something different from what it really is. It seems like a misrepresentation and I am concerned that the Christian witness could be harmed by it.
While it is possible to get the basic information you need to go on the diet from the Daniel Plan website, everywhere you click there is something to BUY NOW. The Daniel Plan Store offers workout wear, towels, water bottles, campaign kits, journals, books, cookbooks, DVDs, audio guides, study guides, etc. As you read about the plan, it's hard not to get the impression (at least it was for me) that you will not be successful unless you use (buy) the tools and resources being offered. This can be an expensive proposition. The marketing is very aggressive and frankly, that disturbs me, too. I kept wondering how devastated the biblical Daniel would likely be if he could see everything being sold in his name and for what purpose. [12, 13]
Finally, many Christians have expressed concern about a pastor actively collaborating with doctors who are proponents and practitioners of Far Eastern religions, meditation, Reiki, the consultation of mediums, and other practices the Bible clearly forbids. Why not seek the advice of Christian doctors instead? Second Corinthians 6:15 reminds us "...what harmony has Christ with Belial, or what has a believer in common with an unbeliever?" First Timothy 3:2-3 declares, "An overseer [bishop or elder], then, must be above reproach, the husband of one wife, temperate, prudent, respectable, hospitable, able to teach, not addicted to wine or pugnacious, but gentle, peaceable, free from the love of money..."
I personally don't recommend a diet plan — even if some people have lost weight on it — if there was a chance that you could be led into confusion or encouraged to practice something that felt wrong spiritually (such as "meditative prayer," using Far Eastern meditation techniques). It's possible to eat healthfully and live an active lifestyle without that influence. [14, 15, 16]
1. Nanci Helmmich; "Rick Warren shares the good news about weight-loss plan
3. Daniel 1:12
4. Definition: corprophagia
5. Northern Ireland Direct; "Beans, pulses, nuts and seeds
6. Pulse (legume)
7. Nanci Helmmich; "Rick Warren shares the good news about weight-loss plan
8. The Daniel Plan Good Foods List
9. "Enjoy God's Abundance
10. The Daniel Plan Plate
11. Nanci Helmmich; "Rick Warren shares the good news about weight-loss plan
11. The Daniel Plan website
13. The Daniel Plan, by Rick Warren, Daniel G Amen, MD, and Mark Hyman, MD. Kindle Locations 842-850
14. Tiffany Myers; "What does it mean to "meditate" on God's Word?
15. Bob Seidensticker "Rick Warren: Is This Really the Way to Help People?