Lipozene is marketed by Obesity Research Institute, that's basically a one-ingredient diet pill containing Glucomannan. Glucomannan is a water soluble dietary fiber that comes from the konjac root - yes, you read that right, it's simply a dietary fiber. Fresh konjac contains roughly 13% dry matter on average and a little over 60% of that dry matter is glucomannan, and 30% is starch.
Glucomannan is a food additive, and commonly used as a thickener. It has been used in asia in traditional foods such as tofu, noodles, and heat stable gelled foods. There are a wide variety of foods containing Glucomannan that's marketed under different brands, and there are also a variety of dietary supplements that contain Glucomannan sold to combat obesity - Lipozene is one such diet pill making Glucomannan its only ingredient. There are also other diet pills that use Glucomannan as an ingredient in its blend of thermogenic ingredients such as Trimspa.
Glucomannan does not dissolve in water. Instead, it forms a gel when mixed with a liquid. It does not get digested by the body, so it is passed through the digestive system. There are various health benefits of Glucomannan that have been studied. It has been found to be helpful in treating obesity, helps lower cholesterol, helps treat constipation, and may also be beneficial in treating diabetes.
Lipozene (Glucomannan) Benefits
As already mentioned, Glucomannan is the only ingredient of Lipozene. There are several health claims made for Glucomannan, and although there are some clinical studies backing up these health claims, they have not been approved by the FDA. Some health benefits of Glucomannan include:
Obesity - there are numerous studies showing the benefit of Glucomannan in treating obesity. More on this later.
Constipation - because Glucomannan is a soluble fiber, it has been studied for the treatment of constipation. There are various studies that confirm the benefit of Glucomannan in treating constipation. In one study involving 7 constipated subjects, the participants consumed Glucomannan over 21 days. They found that bowel movement frequency increased by 30% and also helped improve colonic ecology in the constipated adults .
Cholesterol - Glucomannan has also been studied for its cholesterol lowering effects. One study involving 63 healthy men in a double blind, crossover, placebo controlled study, had the participants consume 3.9g of Glucomannan or a placebo for 4 weeks, while maintaining normal diets. The study found that Glucomannan reduced total cholesterol by 10%, and reduced blood pressure by 2.5% .
Type 2 diabetes - Glucomannan has also been found to be beneficial for individuals with type 2 diabetes. One study found that "In type 2 diabetes, pre-prandial glucomannan ingestion attenuated a rise of blood glucose without significantly affecting insulin levels... Supplement of glucomannan may be beneficial to the glycemic and lipid controls in type 2 diabetes mellitus." 
Does Lipozene Work?
Lipozene contains one ingredient - Glucomannan. Each bottle contains 30 dose, with each dose containing 1500mg of Glucomannan. Sure, Lipozene works, simply because Glucomannan works, and has been shown by scientific studies to have beneficial effects toward weight loss among other benefits mentioned above. However, at the most basic level, you're paying for over priced dietary fiber. =) There are numerous studies that have shown the weight loss benefits of Glucomannan, some are described below.
25 severely obese patients followed 3 months of reduced calorie diet either alone or with a glucomannan supplement. This study found that the Glucomannan group had more significant weight loss compared to the control group. No adverse side effects were reported. 
Another study found Glucomannan to beneficially affect total cholesterol, LDL cholesterol, triglycerides, reduce body weight, but not HDL cholesterol or blood pressure. 
A 8 week double blind trial involved 20 obese patients. A placebo or a glucomannan fiber supplement (1gram) was given to the subjects one hour before each meal. No changes were made to the diet or exercise habits of the patients. The study found that over the 8 week period, cholesterol levels were significantly reduced, and the Glucomannan group had an average weight loss of 5.5lbs. 
These are just a few of the studies done on Glucomannan and weight loss. It is obvious that Glucomannan conveys many benefits towards lowering cholesterol levels and reducing body weight. Lipozene, containing only Glucomannan does work, and can help with weight loss. However, it will not work for everyone. There are users that report no progress using Lipozene. If you consider some of these studies, losing 5.5lb over a 8 week period works out to just under 0.7lbs per week.
But really, when it comes down to it, do you really want to over pay for dietary fiber? I'll leave that up to you. If you look at the overwhelming research performed on the beneficial effects of dietary fiber and management of obesity, it should be quite obvious that increasing your regular dietary fiber intake should lead to a healthier life style along with perhaps some weight loss on the side. As it stands, the average daily fiber intake in the US is half the amount of the recommended daily intake.
There is a large body of studies that cite the benefit of following a fat-reduced, fiber rich, and high in low energy density carbohydrates (ie. whole grains). One study titled "Dietary fiber and body weight" is such an example. The study wrote:
Epidemiologic support that dietary fiber intake prevents obesity is strong. Fiber intake is inversely associated with body weight and body fat. In addition, fiber intake is inversely associated with body mass index at all levels of fat intake after adjusting for confounding factors...
Increasing consumption of dietary fiber with fruits, vegetables, whole grains, and legumes across the life cycle is a critical step in stemming the epidemic of obesity found in developed countries. The addition of functional fiber to weight-loss diets should also be considered as a tool to improve success. 
As you can see, it is obvious that increasing daily dietary fiber intake will convey all the above stated health benefits. As dietary fiber is readily available, and in most cases inexpensive - I see no reason why there's a need to spend extra money on diet pills like Lipozene when you can get fiber from food sources such as fruits, vegetables, whole grains and legumes. Some foods high in fiber include:
This is a rather small listing of foods high in fiber. They're simply listed to illustrate what types of foods are rich in fiber, and that these foods are very common and readily available.
1. J Am Coll Nutr. 2008 Feb;27(1):102-8.
Supplementation of konjac glucomannan into a low-fiber Chinese diet promoted bowel movement and improved colonic ecology in constipated adults: a placebo-controlled, diet-controlled trial.
Chen HL, Cheng HC, Wu WT, Liu YJ, Liu SY.
Institute of Nutritional Science, Chung Shan Medical University, Taichung, Taiwan 402.
2. Am J Clin Nutr. 1995 Mar;61(3):585-9.
Effect of short-term ingestion of konjac glucomannan on serum cholesterol in healthy men.
Arvill A, Bodin L.
Department of Clinical Physiology and Occupational Medicine, Orebro Medical Centre Hospital, Sweden.
3. J Med Assoc Thai. 2007 Oct;90(10):2150-7.
Glycemic and lipid responses to glucomannan in Thais with type 2 diabetes mellitus.
Chearskul S, Sangurai S, Nitiyanant W, Kriengsinyos W, Kooptiwut S, Harindhanavudhi T.
Department of Physiology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok,
4. Minerva Med. 1992 Mar;83(3):135-9.Related Articles
[Chronic use of glucomannan in the dietary treatment of severe obesity]
Vita PM, Restelli A, Caspani P, Klinger R.
Centro per la Farmacoterapia delle Malattie Nutrizionali, Università degli Studi di Milano.
5. Am J Clin Nutr. 2008 Oct;88(4):1167-75.
Effect of glucomannan on plasma lipid and glucose concentrations, body weight, and blood pressure: systematic review and meta-analysis.
Sood N, Baker WL, Coleman CI.
University of Connecticut Schools of Medicine and Drug Information, Hartford Hospital, Hartford, CT 06102-5037, USA.
6. Int J Obes. 1984;8(4):289-93.
Effect of glucomannan on obese patients: a clinical study.
Walsh DE, Yaghoubian V, Behforooz A.
7. Nutrition. 2005 Mar;21(3):411-8.
Dietary fiber and body weight.
Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota, USA.