Now she can have her first routine doctor's appointment for seven years.
"I am so happy," says Sizemore as she waits at the Grace Community Health Centre in Clay County, Kentucky, "I've not had insurance since I turned 19."
But Sizemore is also nervous. She is seriously overweight and was warned in her teens that she was likely to develop diabetes. Without health insurance she has not been able to afford tests or check-ups to see if she has indeed got the disease.
"I'll go to the hospital only in an emergency," says Sizemore, who is still paying off the $10,000 bill for removing her appendix two years ago.
Steven Beshear Kentucky governorThe president is not all that popular in the state - so we don't talk about Obamacare”
Like many, she now qualifies for Medicaid, the government programme that pays for health care for the poorest Americans. Under the new law, the federal government offers states money to expand Medicaid so that many more people on very low wages, like Liberty Sizemore, are covered.
There are also federal funds for new state insurance exchanges where Americans can shop for private plans. Some plans are heavily subsidised by the government, depending on the applicant's income level.
Kentucky is one of a minority of states - and the only one in the South - to have taken Washington's money and embraced all the reforms.
But it has done it without embracing the man after whom they are named.
"The president is not all that popular in the state," says Democratic Governor Steven Beshear, pointing to Mr Obama's 34% approval rating in Kentucky (eight points below the latest national figure reported by Gallup). "So we don't talk about Obamacare," he explains.
Instead, officials talk enthusiastically about Kentucky's own insurance exchange, Kynect.
The governor believes the strategy has paid off. "They came in droves to sign up on the first day and it's been that way ever since."
And yet, misgivings about the biggest health reform in the US in 50 years persist - even among some of those who have benefitted most.
Hairdresser Sadie Smith has enrolled but, she hopes, only as a temporary measure. Her family's insurance disappeared when her husband lost his job. (Most Americans with health insurance get it through their job, with the employer and the worker sharing the cost.)
As she puts the finishing touches to a customer's hair at her small salon in Manchester, Kentucky, Smith says she is grateful for Obamacare. But she is uneasy. "It scares me. The government wants to control everybody - their finances, their insurance, it all comes back to control."
Similar sentiments about government control are behind objections to another Obamacare rule: everyone must have some form of health insurance or risk being fined.
Robert Stivers Kentucky state senatorThey've caused more people to lose their insurance than they helped gain”
He also worries about the long-term cost to the state. The federal government is picking up the bill for the subsidised parts of Obamacare at the moment. But Kentucky will have to start contributing up to 10%, starting in 2017.
Unlike many of his Republican colleagues in Kentucky and Washington DC, Senator Stivers is not calling for outright repeal of Obamacare. "What we are looking for is a reasonable alternative," he says. That includes rolling back the expanded Medicaid coverage and subsidies, and eliminating all the mandates.
But governor Steven Beshear thinks that's unlikely. "We now have 421,000 Kentuckians who are also voters signed up for the law and liking what they are getting," he says.
And the Governor suggests opponents of Obamacare face a predicament. "They want to be critical of the president and his administration, but at the same time they want those 421,000 votes," he says, "so they're not going to take away that coverage from those folks."
Benita Adams may be one of the people the Governor has in mind. The 62-year-old grandmother lives on the edge of the rolling Appalachian Mountains in eastern Kentucky. She owns her home but works two jobs as a dental assistant to make ends meet. She did not vote for President Obama.
Adams has had no health insurance since her divorce 30 years ago. A recent heart operation left her with a $67,000 bill. Although the hospital waived around half of that, she still pays $50 a month to clear the rest.
"I used to say, if I get hurt just let me be killed because I can't afford to pay any more hospital bills," she says.
But Adams no longer has to worry. Under Obamacare, she qualifies for a private insurance plan with a hefty government subsidy that covers the monthly payments in full.
"Everyone was mad over Obamacare but it's just wonderful, it's really helping people," Adams says as she lists the medical appointments she has been to since getting insured.
Of course, Mr Obama cannot run for the presidency again. But if he could, would Adams vote for him? "I'd sure think about it" she says, "It's the best thing he's done."
Liberty Sizemore, waiting for her blood test results at the Grace Community Health Centre, feels the same. As the nurse practitioner delivers the good news, she lets out a long sigh.
Sizemore is close to being diabetic but does not yet have the disease. Her voice trembles as she says quietly, "That's a lot of relief." Then as the nurse gives advice on turning her health around, Sizemore starts to cry.
"I was so worried," she says. "But now I can get better because I have a doctor. I have a doctor and that's a relief off my shoulders, more than you can know."