DEAR DR. BLONZ: I read with interest your article on the Sensa weight-loss product. Although you did not state a definite "yea" or "nay" on the product, I thought I would share that I've been on Sensa for five months and have lost 36 pounds. I was skeptical at first, but am now a firm believer in the product. If you sprinkle it on all foods (except liquids) and drink at least 64 ounces of water a day, you do lose weight. The weight loss is slow, as it should be. Sensa also has an awesome support community online and a coach to answer any questions about the product. Just my two cents. -- J., via email

DEAR J: Thanks for the two cents. I don't often write twice about a particular product, but yours is a wonderful story and you have my congratulations. But in addition, I wanted to explain the basis for my obvious skepticism, which goes beyond this product and is reflective of the field of weight-loss products in general. Namely, my skepticism is based on the lack of reliable, objective evidence affirming the effectiveness of this product -- and many others.

Not to lessen your ongoing accomplishment in the slightest, but you can find individuals who write about successful experiences with most approaches. I look for support that is evidence-based and objective. The testing of a product or theory is only considered objective when it's conducted by individuals who have no association with the success of the method, and one must be reserved in the claims for any product until such evidence has been gathered. What is needed is a controlled test of each method, with the results then written up, put through a peer-review process and published in scientific literature. Until that happens, all we have are products being promoted by those with a financial interest in sales, and associated theories where we don't really know what might be causing what.

For example, you state that you are drinking at least 64 ounces of water a day. A review article in the December 2009 issue of the journal Eating Behaviors reported that increased consumption of water, by itself, is associated with a decreased caloric intake. Granted, none of the studies summarized in that report found that water consumption was associated with weight loss approaching 2 pounds a week, like yours, so something is obviously going on in your case. But does the Sensa produt involve an actual biochemical mechanism that will work for others?

There is also the "you gotta believe" aspect: There is evidence in the scientific literature that a significant part of any approach to weight management is a personal commitment to it and a belief in its efficacy. One using a method because of personal motivation is more likely to be successful than another who is only using the same method at the insistence of another. Marketing and support services can serve as important adjuncts to success, but nothing replaces personal motivation and belief.

You have my wishes for your continued success. Keep me informed of how things proceed.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: My boyfriend works at night and then takes melatonin to help him sleep during the day. For a number of weeks, he has been taking 3 milligrams a day. I told him that I wouldn't personally take it every day, but he said that otherwise he wouldn't get sufficient sleep. His job requires him to be alert, so getting enough sleep is crucial. I have looked up melatonin online but keep finding conflicting information. What do you recommend? -- J.K., San Jose, Calif.

DEAR J.K.: I question the use of melatonin on a regular basis for this purpose, especially if your boyfriend's work schedule is consistent. Melatonin should not be thought of as a sedative or a sleeping pill; it is more along the lines of a hormone that can facilitate "re-education" to reset your body to a new sleep schedule. Once the sleep pattern has been established, it has done its job. There are legitimate concerns about the taking of an unneeded hormone as a part of one's daily regimen.

Our bodies respond to daylight and darkness, and the hormone melatonin plays a role in the sleep/wake cycle. It is released by the pineal gland after we shut our eyes and go to sleep, which usually occurs at night in the dark. Seeing as your boyfriend is sleeping during the daylight hours, the room where he sleeps should be completely dark. If he routinely wakes during his "night" to visit the bathroom, that room should, if possible, be dark as well. When he wakes up at the end of his sleep, he should get some exposure to bright light. If there is no sunlight when he wakes for his "day," he might consider buying a full-spectrum light. The idea here is that he should do his best to educate his body that his pattern is the norm. When it is his sleep time he should avoid computer monitors, televisions, e-readers or tablets with bright screens, as this light can inhibit the body's normal melatonin production. (This is good advice for anyone having trouble getting to sleep.)

Your boyfriend should check with his physician to make sure that melatonin, or any other product, will not present a problem with his health profile. Thinking beyond medicinal fixes, eating well and exercising both help with sleep by decreasing stress, which is a potent sleep-robber. Exercise also helps tweak the body toward a regular activity/regeneration cycle, sleep being where regeneration takes place.

Other ideas: There are a number of relaxation techniques and tapes that may be of help. A warm glass of milk before bedtime is a tried-and-true remedy, as is a warm bath. Tryptophan, an amino acid, may also help -- it's the precursor to the neurotransmitter serotonin, which can encourage relaxation.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: I'm taking several vitamin and mineral supplements and OPCs in what is referred to as an "isotonic form." This form is supposed to be a more efficient delivery system as it goes through the stomach and right to the small intestine, thereby allowing close to 95 percent absorption due to not being diluted by stomach acids. Also, it's said to speed up entry into the circulatory system, occurring within 15 minutes as opposed to four hours or more for a regular pill or capsule. What are your thoughts on taking vitamins and minerals in this form as opposed to a regular pill or tablet? -- C.G., Sun City, Ariz.

DEAR C.G.: "OPC" refers to the tongue-twisting term "oligomeric proanthocyanidins." It's no wonder they stick with the letters. OPCs are naturally occurring bioflavonoids that are found in grape seeds and skins, pine bark extract and other plants. They function as antioxidants, meaning that they attract and combine with reactive oxygen species before they can cause damage. OPCs are being investigated for a potential role in protecting against chronic disease, but keep in mind that supplements cannot replace whole foods and what they have have to offer. With supplements you may get a few standouts, but using a sports analogy, it would be like having a star player without a coach or the rest of the team.

As far as "isotonic" goes, it is questionable who benefits besides the company making the sale. Isotonic means "the same tone," but in physiological solutions, it usually refers to a concentration of ingredients similar to those inside of a cell. The idea of an isotonic liquid is that it will not pull fluids from inside the cell and this may facilitate bioavailability. When they give IV solutions, for example, they usually give them in isotonic saline because they don't want to affect blood pressure or volume or the health of the cells. With dietary supplements, the question one might ask is: What difference does it make if the substance is absorbed slightly faster?

In terms of your product, a 95 percent absorption rate is bogus as a general claim. The rate of nutrient absorption depends on a number of factors, such as the nature of the nutrient; whether the subject already had a deficiency, sufficiency or excess of the nutrient; and other substances present in the digestive system at the same time.

You say it is described as "a more efficient delivery system," but I would be interested in seeing any evidence to support such a claim. Pills, capsules, powders or liquids work just fine -- isotonic forms of dietary supplements have not been shown to be more effective. As a rule, it's usually best to take vitamin and mineral supplements at mealtime. Digestion and absorption are designed to liberate the nutrients from the foods by keeping the food churning and in contact with the absorptive surfaces for an extended period of time.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.