U.S. government guidelines were changed 35 years ago to suggest we lower our fat intake & increase our carb intake. American society followed these recommendations & lowered their fat intake by 11% & increased their carb consumption. In this same time frame obesity, diabetes, heart disease are all at epidemic levels. Through their direct effects on insulin & blood sugar, refined carbohydrates are the dietary cause of coronary heart disease & diabetes.

A low carbohydrate diet is a high fat diet. The protein should only be a little higher than adequate. Although it is completely possible to live on a fat/protein only diet for long term (as proven by research done in a hospital setting) it becomes boring fairly quickly. Luckily many vegetables & some fruits, nuts & seeds are low in carbs & greatly expand the diet. Most long term low carbers eat as many, if not more non starchy vegetables than vegetarians.

Glucose is the bodies preferred fuel (if you want to get technical, it actually burns alcohol most efficiently, but that doesn’t make it any healthier for the body than carbs), the body can convert 100% of carbs, 58% of protein & 10% of dietary fat into glucose. The body can also be fueled by fat (dietary fat & fat cells) but only in the absence of carbs. Your brain actually prefers* to be fueled by ketones (part of the fat burning process), it does require glucose also, but glucose can be easily converted from excess protein if needed or dietary fat.

Plaque build up in the arteries is more attributable to carb consumption than dietary fats, which seems to be the conclusion of the following study. Carb consumption raises triglycerides & VLDL (bad cholesterol). Fats raise the HDL (good cholesterol). High triglyceride levels & low HDL levels are an indicator of plaque & glycation – the precursors to a heart attack & heart disease.

http://heartscanblog.blogspot.com/2009/1…

study from the Oxford group examining the postprandial (after-eating) effects of a low-fat vs. low-carbohydrate diet. (Roberts R et al, 2008)

Postprandial lipoproteins, you’d think, would be plentiful after ingesting a large quantity of fat, since fat must be absorbed via chylomicrons into the bloodstream. But it’s carbohydrates that figure most prominently in determining the pattern and magnitude of postprandial triglycerides and lipoproteins. Much of this effect develops by way of de novo lipogenesis, the generation of new lipoproteins like VLDL after carbohydrate ingestion.

Gary Taubes who wrote "Good Calories, Bad Calories" spent 7 years going through all the studies over the last century & dividing up the real science from the faulty science & concluded that low carb was the best way to control insulin levels which balances out other hormones & allows the body to function properly.

His main points are:

1. Dietary fat, whether saturated or not, is not a cause of obesity, heart disease or any other chronic disease.

2. The problem is refined carbs in diet, their effect on insulin secretion & the hormonal regulation of homeostasis.

3. Sugars – sucrose, high-fructose corn syrup specifically – are particularly harmful, the combination of fructose & glucose simultaneously elevates insulin levels & overload liver with carbs.

4. Through their direct effects on insulin & blood sugar, refined carbs, starches, sugars are the dietary cause of coronary heart disease & diabetes. They are likely dietary causes of cancer, Alzheimer’s & other diseases.

5. Obesity is a disorder of excess fat accumulation, not overeating.

6. Consuming excess calories does not cause us to grow fatter.

7. Fattening & obesity are caused by an imbalance in the hormonal regulation of adipose tissue & fat metabolism. Fat synthesis & storage exceed the mobilization of fat from adipose tissue & its subsequent oxidation.

8. Insulin is the primary regulator of fat storage. When insulin levels fall, we release fat from fat tissue.

9. By stimulating insulin secretion, carbs make us fat.

10. By driving fat accumulation, carbs also increase hunger & decrease the amount of energy we expend in metabolism & physical activity.
References :
*
The brain gets its energy from ketone bodies when insufficient glucose is available. After blood glucose is lowered for 3 days, the brain gets 30% of its energy from ketone bodies. After 40 days, this goes up to 70% (during the initial stages the brain does not burn ketones, since they are an important substrate for lipid synthesis in the brain). In time the brain reduces its glucose requirements from 120g to 40g per day.

Ketones have been described as "magic" in their ability to increase metabolic efficiency, while decreasing production of free radicals, the damaging byproducts of normal metabolism. The heart and brain operate 25% more efficiently using ketones as a source of energy

http://en.wikipedia.org/wiki/Ketone
Taubes Lecture -
http://www.dhslides.org/mgr/mgr060509f/f…
http://www.drbriffa.com/blog/2010/01/15/two-major-studies-conclude-that-saturated-fat-does-not-cause-heart-disease/

So it’s a good starting point to check this report out.

Good luck for your GF!
References :
http://dietmythsexposed.info

Listen to the long description described by the user posted earlier.His advice is sage, and i’ve seen his posts before. I suggest you follow it.
References :

Only 15% of what you eat contributes to your body cholesterol total number. 85% is made in the liver and for good reason. If you eat less cholesterol in your diet, your body just makes more to compensate for the lack of it in your diet. ALL your steroid hormones are made from cholesterol. ALL OF THEM. That is testosterone, ESTROGEN, pregnenalone, progesterone, CORTISOL, etc. are all steroid hormones that require cholesterol for synthesis in the body. If you have too little cholesterol, you won’t be transporting those fatty acids well in the body and it will contribute to slow healing.

Think about this, Lipitor that doctors are recommending and prescribing at unprecedented rate. These statin drugs like Lipitor, lower cholesterol by inhibiting HMG-CoA reductase, a key enzyme in cholesterol synthesis. In many cases these drugs activate the Atrogin-1 gene that plays a key role in muscle atrophy. Three separate tests showed that even at low concentrations, statin drugs led to Atrogin-1 induced muscle damage. As the concentrations increased, the damage increased as well.

Your heart is a muscle. Does it make sense to turn on that Atrogin-1 gene that induces muscle damage? The drug turns off the synthesis of CO-Q-quinol in the body as well. Every cell in the body needs this for energy management of the cells. This is very bad science and just shows how little medical science understands about how the body works.

There are some very good books on this subject that are written by true experts in the field of fats and oils. Mary G. Enig, Ph.D. is one of them. She is almost single handedly responsible for testifying before congress to expose TRANS FATS. She worked on this for 15 years before making any headway on this subject. Read her books if you want the truth about this cholesterol myth that drug companies are pushing so heavily.

good luck to you
References :
CNT, B.A. biology & chemistry
advanced nutritional research