DEAR DR. BLONZ: At a holiday dinner party, the host and their friends began talking about a line of health products they sell. I hadn't understood this was the theme of the night, and I remain the only holdout. The main product is an anti-aging stem cell product. A doctor heads the company, and there are many testimonials, and those friends are making a bit of money. Below are links to the site. Do you have any policies or recommendations? -- B.B., San Diego, California

DEAR B.B.: I commend your well-founded skepticism. It's difficult for a trained professional, let alone the public, to keep up to date with all the dubious health-related product-promoting schemes that now pervade social media. I checked out the links (not included here) with all their promises and found nary a hint of clinical evidence to back them up. There's also limited information on the products' ingredients.

The individual in charge goes by "Doctor," but it never reveals what type of doctor. It says he is a leading, internationally known nutrition authority. Questions that come to mind include, "known by whom?" and "Where is he leading people?" There are ways to buy "Ph.D" credentials online with no classroom attendance required. They give credit for "life experience," but the main qualification is a willingness to pay. I recall when an academic colleague was able purchase a graduate degree for his dog!

Your party used a multi-level marketing (MLM) technique, often called a pyramid scheme. This marketing technique combines online elements with neighbor-to-neighbor selling, often seeking to recruit individuals onto their team (where the team leader profits from all sales). I've found that when health-related products are offered with promises of cures and profits, any demand for proof of efficacy takes a back seat. MLM plans typically involve the use of testimonials as evidence. Pitches follow the line that "it worked for them, so why not for you?" Add a pseudo-credentialed "Dr." and social pressures, and you end up with impressive marketing clout. For more on MLM, see b.link/x3t8mcd.

It's deceitful to claim expertise without training. And when the practice involves a health-related area, it can be dangerous. There is no effective way to purge all fraudulent practitioners from health care -- and AI has added a level of complexity -- so it falls upon us to remain vigilant. Resisting what is portrayed as a financially successful venture may not win you a popularity contest, but, absent objective evidence of efficacy, it remains the right thing to do.

Finally, always remember that quick fixes rarely work in the long term. They tend to raise your hopes and lower your bank balance, while creating the risk of unknown side effects and interactions with other products you're taking, or with existing health conditions and medications you're using. There is also the more insidious element that a treatable ailment progresses to a more advanced stage while untested products are given their try. For more on health fraud, see the article at b.link/7kwp2hx.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 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 want to lose weight without a prescription drug. I am seeking information on fat-burning foods or supplements that are promoted for a claimed ability to help weight loss by making the body burn fat while you sleep. What about caffeine and herbal stimulants (not taken at night, of course)? Thank you in advance for your help. -- G.E., Raleigh, North Carolina

DEAR G.E.: There is no evidence of a meaningful increase in fat loss during sleep from adding specific foods. The "fat-burning food" label is mostly nonsense. Diet and sleep do interact, but the main levers are when and how much you eat, not magic nighttime foods.

Fat is metabolized (burned) as part of normal energy metabolism. To burn more, we must expend more energy, for example, through exercise and other forms of muscular work.

It is best to avoid turning to "stimulant" supplements, such as caffeine or guarana, for weight loss. The body needs rest to repair, regenerate and clear metabolic waste. It produces substances that promote rest when this is the case. The key calming substance is adenosine. Receptors on cell membranes respond to adenosine's presence by activating our metabolic brakes. Caffeine can bind to adenosine receptors and prevent the slowdown. While caffeine is thought of as a stimulant, it does not stimulate so much as it blocks the action of receptors that slow things down.

A reasonable intervention for weight loss without drugs is healthy eating combined with regular physical activity. Exercise not only burns calories, but it can also increase muscle mass, which has the added benefit of making the body burn more calories than other tissues, even at rest.

Regarding sleep, we all lose weight while resting. The only time we are not losing is when we are eating and drinking. The longest "fast" of the day is -- you guessed it -- when we are asleep! (Also, that's why the morning meal is named "breakfast" -- we "break" the "fast.") The idea, however, that a supplement will help you to drop a few sizes while you slumber is pure folly. For more on herbal remedies and weight loss supplements, see b.link/4vdmugu.

DEAR DR. BLONZ: What controls how much cholesterol the body manufactures? Can it make more cholesterol than it gets from food? -- E.D., Ames, Iowa

DEAR E.D.: Cholesterol is an essential structural component of every cell in the body. Even if there was no cholesterol in your diet, your body would have to make it. In addition, cholesterol is a precursor for several hormones, including estrogen and testosterone. Most of the cholesterol is manufactured in the liver. When cholesterol is present in the foods we eat, the liver is programmed to make less. There are several genetic conditions in which the body produces more cholesterol than it needs. Referred to as familial hypercholesterolemia, they tend to be rare (for more on this see b.link/smgfxsp).

More common, however, is the condition in which the body receives an unbalanced diet that's heavy on the carbs and processed foods and light on the whole food fresh fruits, vegetables and high-fiber grains. This results in blood cholesterol levels that are way out of whack. For more on using diet to lower cholesterol, see b.link/ypvky3a.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 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 am in relatively good shape for one in their 50s, and I eat well. I walk and exercise regularly, but not as much as I did earlier in life. Like many others in my group, I am annoyed by the weight around my middle. I can't improve my diet much more, and am frustrated at the bulge. Nothing has really changed except the shape of my body?! Any advice you can offer on aging, calories, and specific exercises would be appreciated. -- T.T., San Jose, California

DEAR T.T.: With aging, there is a natural decline in the energy (calories) the human body requires. There is also a tendency to decrease activity. Both contribute to changes in body shape, especially with individuals who continue to consume the same (or more) amount of calories, particularly if more processed foods with added sugars have entered the mix. There is also the fact that our body weight is packed into a smaller frame due to age-related loss of height from reductions in bone mass and increased spinal compression. (For more on the effects of aging on body shape, see b.link/2a3d3ay.)

There are three basic elements to our daily caloric demand. First and foremost is the resting metabolic rate (RMR). This is energy needed to keep the body alive, but not to fuel activities. Consider this our "cost of living," which represents about 60% to 75% of the daily caloric requirement. Next is the energy used for physical activity. For an average individual, this is about 15% to 30% of the calories we need. Finally, we have the thermic effect of food (TEF), also called thermogenesis, the energy released as heat as we eat and digest food. TEF accounts for about 5% to 10% of our daily calories, and tends to be higher in those with regular exercise habits. (More on thermogenesis at b.link/gls72y2.)

Fewer calories are burned by an aging body than its younger version, even if eating and physical activity remain the same. This age-associated decline is not solely attributable to the loss of lean body mass (muscle, organ and bone) that accompanies aging.

Muscles burn calories even when you are lying around, so do your best to maintain your muscle mass to help slow any age-related decline. (Think of the difference between the gas burned by a 4-cylinder engine idling at a stop light versus an 8-cylinder doing the same.)

The cumulative effect of stress can also contribute to that unwanted midline bulge. The body reacts to stress by bringing fuels into the blood to prepare for action. This occurs even if the stress is psychological and won't require a physical response. Ephedrine (adrenaline) and norepinephrine are the stress hormones that increase fuel levels. Cortisol is the stress hormone that helps calm things down and return blood fats to storage. Receptors in the abdominal area are more sensitive to cortisol, which can lead to greater fat accumulation in that area when stress is habitual.

Keep up with your activities. There should be elements of both aerobic workouts and resistance exercises to maintain your muscle mass. Consider speaking with a trainer to see if there are specific exercises to help with muscle tone in problem areas. Working on your core muscles is particularly helpful as it supports the back, another aging-associated issue we want to stay ahead of.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 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.