Whether you observed quietly as all your friends tried the grapefruit diet, or you whip out flax seeds at every meal, food and diet trends have a way of creeping into our lives (and stomachs) every few years.

Thanks to day-time talk shows and the Internet, figure-conscious consumers are constantly inundated with the latest foods and supplements promising to cure all our health woes and make us thin. While the jury is still out over the effectiveness of many of these products, one thing is for sure: they don’t come cheap.

Before you spend your hard-earned cash on products promising a new and improved you, take a look at our list to make sure you know what you’re getting and how much you can expect to pay. We checked in with health and fitness experts to get the skinny on some of the more expensive items that claim to help get you get thin.

Raspberry Keytones 

“Anything with Raspberry Ketone in the ingredients list has been flying off the shelves since Dr. Oz mentioned it as a serious fat burner on his show,” says Tyler Spraul, spokesperson at WeightTraining.com. “On the day he first mentioned it, stores sold out within a few hours. The demand means higher prices for now.”

What it does: According to Spraul, raspberry keytone is supposed to help your body break up fat more effectively, and thus burn it faster.

How much it costs: 180 capsules of 125mg Raspberry Ketone from Raspberry Ketone retails for $39.95 at Amazon.com.

Whey Protein

For athletes, the go-to is always whey protein, says Spraul. The protein is more effectively absorbed when it’s in “concentrate” or “isolate” form, which basically means it’s been filtered.

“They pay top dollar for the filtration process—it’s an average markup of 300%,” he says.

Dr. Amy Lee, a Los Angeles-based doctor and dietician, adds that whey protein is imported from New Zealand, which adds to its cost.

“Many people think the best whey protein is from New Zealand, made from the milk of New Zealand cows. Everyone is trying to get their hands on it, and it’s expensive.”

What it does: This animal protein is supposed to ingest faster in the body than other forms of protein, and offers amino acids necessary for muscle building and post-workout recovery, says Lee.

How much it costs: A 2-pound jar of High Whey New Zealand whey protein from Dr. Dave’s Stages of Life costs $71.99.

Chia Seeds

"Chia seeds are really popping up more and more - on their own, in bar form, and as ingredients in cereal blends. I even just tried a chia seed drink yesterday,” says Brian Tockman, head of merchandising and operations at organic online market AbesMarket.com. The seed, which originated in South America, is one of the hottest sellers on the site, and bottles of cold pressed chia seed oil sell for $50 and up. 

What it does:  “Mayan, Aztec and Incan cultures have used the for thousands of years to increase endurance and strength, and chia seed oil has more Omega 3's than even flax seed oil,” says Tockman.

How much it costs: Cold pressed chia seed oil by eSutras Organics costs $50 for an 8-ounce bottle, and raw organic chia seeds cost by Foods Alive costs $23.07 for 8 ounce, at Abe’s Market.

Turmeric

Turmeric is one of the up-and-coming things that many health professionals are talking about, according to Lee.

“It’s a common spice in India and in Asian cultures,” she says. “It’s something that oncologists recommend for its antioxidants and cancer-fighting abilities, but it’s really not cheap.”

What it does: “Different data has shown that turmeric is an anti-mutagenic herb, that it has incredible antioxidant powers,” says Lee. “There’s a big craze around it now because studies have shown it can actually stop the growth of cancer.”

How much it costs: 240 capsules of 900mg of Vitacost turmeric cost $63.99 at Vitacost.com

Gogi Berries

“’Gojiberry’ is one of the most-searched ingredients on AbesMarket.com and has been touted for its nutritional and healing value,” says Tockman. 

On average, items that include goji berries like gogi berry granola are more expensive than other varieties. 

What it does: “Gogi berry has been used in traditional Asian medicine for centuries,” says Tockman. It’s typically touted for its antioxidant value, and nutritional value as it’s high in vitamin C, iron, zinc, and calcium.

How much it costs: A 32-ounce bottle of Genesis Today Total GOJI Pure Berry Juice costs $37.69 at Vitacost.com.