Yes low fat diets are dangerous as fat is needed for all body functions, but in an unprocessed and unheated plant form. Incidentally animal fats are high in trans-fatty acids so your source is either misleading you or ignorant of real nutritional facts.

Yes you can lose weight on any diet including high protein diets, but  your health will deteriorate, I have yet to find someone who does not develop some health problem somewhere down the line. Extracted from “Perfect Weight - The Natural Way” by Mary-Ann Shearer

HEART ASSOCIATION WARNS OF RISK IN HIGH-PROTEIN DIETS

"Despite their popularity, high-protein diets aren't
making good on their promise of long-term weight loss, says
a new scientific advisory from the American Heart
Association. Moreover, the AHA says the diets are a health
risk for people who stay on them beyond short periods of
time. 'In general, quick weight-loss diets don't work for
most people,' says Robert H. Eckel, M.D., co-author of a
scientific advisory from the AHA'S nutrition committee.
It's important for the public to understand that no
scientific evidence supports the claim' that these diets
work, Dr. Eckel says.

"In 1998 the AHA 'declared war' on fad diets for
misleading claims of instant weight loss. But Tuesday's
advisory was the result of scientific documentation that
gives credibility to the AHA's nutritional guidelines. The
advisory specifically targets the Atkins, Zone, Protein
Power, Sugar Busters and Stillman diets. Over the past
decade these 'quick weight loss' regimens and their authors
have topped best-seller book lists and have been promoted
predominantly in the mass media.

"Some of the diets increase fat intake and reduce
nutritionally rich foods such as fruits and vegetables,
which is not a good approach to meeting a person's long
term dietary needs,' says Dr. Eckel, immediate past chair
of the AHA'S nutrition committee. 'Many of these diets fail
to provide essential vitamins, minerals, fibre and other
nutritional elements, in addition to their high fat
content.' Eating large amounts of high-fat animal foods
over a sustained period has been shown to increase the risk
of coronary heart disease, diabetes, stroke and several
types of cancer, the advisory says.

"The statement notes that a diet rich in animal protein,
saturated fat and cholesterol raises LDL (bad) cholesterol
levels--an effect that is compounded when high-carbohydrate,
high-fibre plant foods that help lower cholesterol are
limited or eliminated. In the Atkins and Protein Power
diets, the AHA is disturbed by the intake of saturated fat
and cholesterol, as well as the risk for heart disease and
stroke. Although the Zone, Sugar Busters and Stillman diets
have lower fat, they are still high in protein, raising
concern of kidney disease, particularly in people with
kidney ailments and older adults with diabetes.

"Dr. Eckel says the public and health-care professionals
should consider the possibility that these diets are
associated with osteoporosis and cancer, although those
links have yet to be scientifically substantiated. [Because
of] the lure of the fad [diets], more than half of all
adults in the United States are either overweight or obese.
'Many of these people are looking to high-protein diets as
a popular 'new' strategy for successful weight loss,' Eckel
says.

"These diets cause a drop in weight primarily through loss
of body fluids caused by the diuretic effect of eliminating
most carbohydrates. Glycogen, the form of sugar used by the
body for energy, is lost from the muscles as well,
sometimes causing fatigue. Some of the diets also cause
ketosis, a metabolic condition associated with low blood
levels of insulin that results when the body is deprived of
dietary carbohydrates.

"Sustained ketosis also causes a loss of appetite, which
may lead to lower calorie intake. Matthew W. Gillman, M.D.,
associate professor of ambulatory care and prevention at
Harvard Medical School and its Harvard Pilgrim Health Care
affiliate, endorses the AHA advisory. 'Because Americans
often get lured by the fad and don't see the dangers in
going to extremes', Dr. Gillman says, ' . . . we should be
considering eating reduced amounts of the refined
carbohydrates, but maybe not less carbohydrates overall.
Try, for example, eating whole grain breads, brown rice,
and cereals that are high in fibre.' But clearly, the quick
fix promised by the high-protein diets is not the way to
go, the AHA says. Studies consistently show that keeping
weight off happens when people follow a nutritionally sound
diet and increase physical activity to burn more calories
than they consume.

"Experts recommend following current AHA guidelines on
nutrition: a variety of foods, including fruits and complex
carbohydrates such as breads, cereals, starchy vegetables,
rice and pastas. . . . "

These five natural way steps will help you find the right balance from a carbohydrate and alkaline forming approach. Start with at least one of them today as you keep reading and making small adjustments rather than one huge change.

1. Eat at least one fruit meal per day

2. All snacks should be fresh or dried fruit or vegetables

3. Try to eat no more than one animal protein meal a day

4. Start all cooked food with some raw vegetables

5. Try not to eat a concentrated protein with a concentrated starch at the same meal.

Incidentally, who ever your source is has neglected to inform you that Dr Atkins died a few months back (April 2003), supposedly from slipping on a pavement, (info from the billion dollar Atkins diet organisation, who are now sitting with millions of his diet books and no guru to promote them) . Exactly a year before in April 2002 Dr Atkins went into cardiac arrest and claimed it had “nothing to do with diet” but was just a condition he developed.  Rumour has it that he died from a heart attack, but the Atkins research Centre has covered up the real cause of death.

“In 1999, Atkins established the Robert C. Atkins Foundation to finance diet research. It has sponsored research at Duke University, the University of Connecticut and Harvard.
       Last April, Atkins was hospitalised for cardiac arrest, which he said was related to an infection of the heart and was not related to the diet.”

Possibly the info (research) you have is from Dr Atkins foundation, it certainly sounds like it, especially when you read the info below.

“In 1999. Atkins set up a foundation to provide "funding for research and education on the role of controlled carbohydrate nutritional protocols in treating and preventing a wide range of medical conditions." [9] In 2002, a 6-month study funded by Atkins found that followers of the Atkins diet lost more weight than comparable people on a high-carbohydrate diet and improved their blood cholesterol and triglyceride levels [10]. However, the dropout rate was much higher in the low-carbohydrate group and the improved lipid levels did not necessarily mean that the diet would have a cardio protective effect in the long run [11]. In response to publicity about the study, the American Heart Association cautioned:

• A high intake of saturated fats over time raises great concern about increased cardiovascular risk. The study did not follow participants long enough to evaluate this.
• The study did not actually compare the Atkins diet with the current AHA dietary recommendations [12].