The average woman eats 4-5 pounds of lipstick in her lifetime.

According to this 1990 statistic from Simmons' 1990 Media and Market Study:
Percentage of women who wear lipstick every day: 75

Number of times the average lipstick-wearer applies it daily: 2

Percentage of women who re-apply their lipstick more than eight times in an average day: 13

So, 75 percent of women use lipstick twice a day for 60 years. That's 43,800 uses of lipstick per woman in that 75 percent of women group. Each tube of lipstick is about 4 grams, and takes about 2-3 months to finish, with each tube having about 450 uses. The legend says that an average woman finishes about 6 tubes of lipstick per year, 360 tubes in your lipstick life of 60 years, which doesn't seem like that much. But the word "finish" needs to be pulled back. A woman might buy 360 tubes of lipstick in her life, about 3.17 pounds, but she probably won't finish them completely to the bottom. If each lipstick is 450 uses, and a woman on average applies 43,800 times in a life, that comes out to less than a pound possibly ingested.

And who's saying she's ingesting all of this anyway? She's definitely "eating" some, which isn't good, as there have been numerous tests concerning the amount of lead deposits in lipstick. But she isn't eating it all.

Men, your ladies are probably consuming 4 pounds of lipstick in her lifetime — as in spending money on it as a consumer — but she isn't necessarily pounding back the LipSmackers.

Basically, this urban myth isn't completely ridiculousness, it's just an exaggeration. The statistic assumes that the average woman applies more than 12 times a day and ingests every last bit of her lipstick tubes, and as we can see from that good ole 1990 statistic up top, it's just not the case. Entirely.