Why not?  Fat is good for you.  Here's why.

Fat is an amazing fuel source. It satisfies; it makes everything taste better. It is uniquely satiating. Saturated fat (the majority of the fat in butter, cheese, and meat) is very stable and thus is a great choice for cooking. Here are more of the amazing properties of fat:

• Controlled, clinical trials tell us that high-fat diets are more effective for weight loss than low-fat diets.
• Fat is a neutral calorie source -- it has no effect on blood sugar. Your body does not have to produce  insulin to digest fat, so fat is easy on your pancreas.
• Saturated fat raises HDL (good cholesterol).
• Saturated fat lowers triglycerides (you want these low).
• Saturated fat changes the profile of your LDL (bad cholesterol), making it lighter, fluffier, and less likely to cause atherosclerosis.
• Saturated fat is important for vitamin and mineral absorption, including calcium and Vitamin D.
• The nervous system needs natural fats. Dietary saturated fat is linked to better mood and mental health, not to mention avoiding dementia and Alzheimer's disease.
• Saturated fats make up our cell membranes, which are important gatekeepers for all of our cells.
• Saturated fat is antimicrobial and fights viruses and bacteria in the digestive tract. Eating more means fewer colds and bugs.
• Saturated fat is safe. Humans have been eating saturated fat for millennia. Scientific studies show that eating saturated fat does not cause heart disease.

Fat is not fattening. Weird, but true.

Most people worry that eating fat will make them fat. And it's no wonder-- we have been told this for decades. And, we know that fat has more calories per gram than carbohydrates or protein. So the assumption is that fat makes you fat. Why, then, as we have cut back on fat, especially saturated fat, have obesity rates tripled?

Our bodies are incredibly complex. Hormones play a huge part in regulating everything, and body weight is no different. It turns out that if you want to burn your own body fat for energy (which is essential if you want to lose weight), you must have low insulin levels. Insulin, you see, tells fat cells to pull fatty acids out of the blood and to keep fat in the fat cells. Whenever you eat carbohydrates, you body floods your bloodstream with insulin. So eating more carbohydrates means less time in fat burning mode. Which means more fat accumulation in the fat cells. Which means hunger and weight gain. Eating more fat and fewer carbohydrates means easier fat burning, less hunger, and a better shot at losing weight.

Leptin is another hormone important for feeling satiated. But insulin dominates, and interferes with leptin's ability to make you feel full and satisfied. So, when insulin is present, due to excess consumption of refined carbohydrates, it turns off leptin's signals, leaving you unsatisfied and on the road to weight gain.

Repeat after me:  Eating refined carbs makes you fat.  Eating good fats makes you thin.

More from the experts:

Dr. Andreas Eenfeldt on how Low Carb High Fat works to reduce weight.

Infographic from Gary Taubes and Massive Health about why fat doesn't make you fat.

Your blood work.

HDL. LDL. Triglycerides. Fasting glucose. Pattern A vs. pattern B. What matters, what doesn't? And why does the answer seem to keep changing?

Nothing has confused Americans more than the confusing advice we have been given regarding diet, cholesterol, and heart disease. Scientists learn more every month. The complete picture is far more complicated than it was when presented three decades ago when we were all told to try to lower our total cholesterol. In 2015, the understanding is much more nuanced, and total cholesterol has become an all but meaningless number, except in extreme cases of hyperlipidemia.  

Here are some basic facts that might help you worry less about your blood cholesterol:

Good news about eating more saturated fat:

• High HDL ('good cholesterol') is strongly correlated with heart health. (Eating less whole wheat bread and more butter raises HDL.)
• Low triglycerides are strongly correlated with heart health. (Eating less whole wheat bread and more butter lowers triglycerides.)
• Happy, fluffy LDL (Pattern A) does not seem to promote atherosclerosis. (Eating less whole wheat bread and more butter increases happy, fluffy LDL.)
• For women, higher total cholesterol is associated with less mortality. (Eating less whole wheat bread and more butter will raise total cholesterol.) See graph, below, or link to NHLBI data - table 3, page 1050.

Bad news about eating more saturated fat:

• Higher LDL ('bad cholesterol') is weakly (4X less predictive than high HDL and low triglycerides) correlated with more heart disease, although this is increasingly viewed as a Pattern A/Pattern B difference. (Eating less whole wheat bread and more butter slightly raises LDL cholesterol.)

Links to more information on cholesterol:

From Dr. Peter Attia on his personal blog, theeatingacademy.com:

What is Cholesterol?

The Straight Dope on Cholesterol - Part I  (Note that you can keep reading... there are nine or ten parts, but it all gets very technical...)

And, from Mark Sisson on his blog, marksdailyapple.com:

The Definitive Guide to Cholesterol

How to Interpret Cholesterol Test Results

A 50 minute lecture about cholesterol from Dr. Jeffry Gerber, a member of the American Society of Bariatric Physicians:

2014 was a very good year for saturated fat.

Many scientists now believe that saturated fat does not cause heart disease. Increasingly, the finger of blame is pointed at refined carbohydrates. This year, several major studies and an award-winning book cast even more doubt on the wobbly evidence against eating natural fat. In fact, dozens of modern clinical trials show that both weight loss and cardiovascular risk factors improve on high fat diets. These results contradict the unproven hypothesis, called the Diet-Heart Hypothesis, that was floated in the 60's, suggesting that eating saturated fat caused heart disease. As more and more clinical trials test this hypothesis, more and more evidence mounts that the hypothesis should be rejected. Unfortunately, the USDA, the American Heart Association, and the American Medical Association have all based their dietary advice on this questionable hypothesis for over three decades.

New Meta-analysis says saturated fat does not cause heart disease.

In March, 2014, cardiovascular epidemiologist  Dr. Rajiv Chowdhury, out of Cambridge University, released a meta-analysis that reviewed over 80 studies, with more than 500,000 participants, representing decades of research and billions of research dollars. His conclusion?

Don't follow the USDA's Dietary Guidelines.

Sometimes mothers are rule followers. But sometimes we are not. Why follow guidelines that don't work for most people? Guidelines that many scientists think are causing obesity and illness? Take back your plate. Give your children a better chance at a future without metabolic syndrome and weight issues. Return to vintage eating. Just eat the butter.

Early this year, the USDA reversed itself on the subject of dietary cholesterol. It softened the decades-long recommendation to sharply limit cholesterol -- a recommendation that caused Americans to reduce consumption of  a real food like eggs, which are high in cholesterol. Why the change? Because experts have known for decades that the cholesterol that you eat doesn't meaningfully affect your blood cholesterol. So why was it limited before? Who knows? 

The USDA has been wrong before. Does anyone remember the 'heart healthy' margarine ads from the 70's and 80's? In those ads, produced by Parkay, Promise, Imperial, Fleishman's, and Mazola margarine, among others, trans-fat-filled products were sold to the American people as 'heart healthy.' We now know that trans-fats actually contribute to heart disease, and the USDA's recommendations that allowed margarine to be sold as 'heart healthy' brought millions to an earlier grave from heart disease. So why believe the USDA now, when modern science does not back up its claims? And, if you haven't looked around lately, our health outcomes certainly do not support the notion that low-fat eating is healthy.

Here is a story worth thinking about. In 1957, a doctor named Alice Stewart published a peer-reviewed paper demonstrating a strong statistical link between the practice of taking x-rays of pregnant women and the development of childhood cancer in the children who had been x-rayed in utero. Unfortunately, it took the American and British Medical establishments 25 years to abolish the practice of routinely x-raying pregnant women. Why? Because change is hard for bureaucracies. And, because people were excited about x-ray machines. And because of professional inertia. And, I hate to say this, but doctors don't like to admit mistakes and egos (gasp!) are involved.  Watch Margaret Heffernan, organizational change expert, tell this story on the TED stage.

It is hard to believe that 40 years of dietary advice to avoid saturated fat was mistaken, but to ignore this possibility is a missed opportunity.

What is new in the 2015 Dietary Guidelines?  

The 2015 Dietary Guidelines for Americans were issued January 7, 2016. A little late, yes, as their typically uneventful redrafting was unusually controversial this time around. What ensued:

• A very public thrashing of the Dietary Guidelines (and the process by which they are crafted) has ensued in prestigious medical journals such as of the Journal of the American Medical Association, British Medical Journal, and Annals of Internal Medicine.
• As a result, the House Full Committee on Agriculture held public hearings on October 7th, 2015 to take up the controversial 2015 Dietary Guidelines.
• Congress weighed in this December, requiring the USDA to hire the National Academy of Medicine to review the Dietary Guidelines, stating “The entire process used to formulate and establish the guidelines needs to be reviewed before future guidelines are issued.”

Going back to vintage eating, the way we ate before there were national dietary guidelines, is a potential path back to vibrant health.

Policy is not science.

There was never anything close to consensus regarding the recommendation to adopt a low-fat diet. Even back in the 60's, when these dietary guidelines were taking shape, many doctors and nutrition experts believed refined carbohydrates were the dangerous nutrient. Even more believed that there was just not enough real evidence for the government to make any sort of recommendation. But the policy was made and our diets changed. And people got fatter and sicker. Now is the time to change our diets back to vintage ways. Real food and more fat is a path that worked 50 years ago and might work for you and your family right now. Try it. Here are some options.

Meta-analyses of the connection between Dietary Saturated Fat and Cardiovascular Risk Factors.

(These are analyses that combine results from many different studies.)

2014

Chowdhury, Rajiv, et al.; Cambridge University

Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk: A Systematic Review and Meta-analysis  Ann Intern Med. 2014;160(6):398-406. doi:10.7326/M13-1788

Conclusion: Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats.

 2012

Santos FL, et al.; Portugal.  including co-author W.S. Yancy, jr. (Duke –Yancy only)

Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors. Obes Rev. 2012 Aug 21. doi: 10.1111/j.1467-789X.2012.01021.x.

Conclusion:  LCD (low carbohydrate diet) was shown to have favorable effects on body weight and major cardiovascular risk factors; however the effects on long-term health are unknown.

 2012

Kratz M, et al. -- Division of Public Health Sciences, Fred Hutchinson Cancer Research Center& University of Washington (Seattle)

 The relationship between high-fat dairy consumption and obesity, cardiovascular, and metabolic disease. European Journal of Nutrition, Online First™, 18 July 2012

“The observational evidence does not support the hypothesis that dairy fat or high-fat dairy foods contribute to obesity or cardiometabolic risk…”

 2011

Hooper L, et al. – Cochrane Collaboration….University of East Anglia, Norwich Medical School, Norwich, UK

 Reduced or modified dietary fat for preventing cardiovascular disease. Cochrane Database Syst Rev. 2011 Jul 6;(7):CD002137.

“There were no clear effects of dietary fat changes on total mortality or cardiovascular mortality…” 

2010

Siri-Tarino PW, et al.  – Children's Hospital Oakland Research Institute Oakland CA; Harvard School of Public Health

 Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr. 2010 Mar;91(3):535-46.

“…no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD.”

 2009

Mente A, et al.  – Population Health Research Institute, Hamilton Health Sciences (Ontario, Canada)

 A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease. Arch Intern Med. 2009 Apr 13;169(7):659-69.

“Insufficient evidence of association is present for intake of … saturated or polyunsaturated fatty acids; total fat … meat, eggs and milk.”

 Controlled clinical trials that show better weight loss with low-carb diets than with low-fat diets.

 (In addition, most show more improvement in cardiovascular risk factors with low-carb diets.)

1. Bazzano, Lydia A., et al. Effects of Low-Carbohydrate and Low-Fat Diets:  A Randomized Trial.  Ann Intern Med. 2014;161(5):309-318. doi:10.7326/M14-0180. (Tulane University PH/Kaiser Permanente; Johns Hopkins PH – NIH funding)
2. Shai I, et al. Weight loss with a low-carbohydrate, mediterranean, or low-fat diet. N Engl J Med 2008;359(3);229–41.  (Ben-Gurion University of the Negev, Israel.)
3. Gardner CD, et al. Comparison of the Atkins, Zone, Ornish, and learn Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women. The a to z Weight Loss Study: A Randomized Trial. JAMA. 2007;297:969–977.  (Stanford University)
4. Brehm BJ, et al. A Randomized Trial Comparing a Very Low Carbohydrate Diet and a Calorie-Restricted Low Fat Diet on Body Weight and Cardiovascular Risk Factors in Healthy Women. J Clin Endocrinol Metab 2003;88:1617–1623.  (University of Cincinnati; Children’s Hospital Medical Center, Cincinnati)
5. Samaha FF, et al. A Low-Carbohydrate as Compared with a Low-Fat Diet in Severe Obesity. N Engl J Med 2003;348:2074–81.  (Philadelphia Veterans Affairs Medical Center; University of Pennsylvania Medical Center)
6. Sondike SB, et al. Effects of a low-carbohydrate diet on weight loss and cardiovascular risk factor in overweight adolescents. J Pediatr. 2003 Mar;142(3):253–8.  (Schneider Children's Hospital, New Hyde Park, New York)
7. Aude YW, et al. The National Cholesterol Education Program Diet vs a Diet Lower in Carbohydrates and Higher in Protein and Monounsaturated Fat. A Randomized Trial. Arch Intern Med. 2004;164:2141–2146.  (Agatston Research Institute; Mount Sinai Medical Center–Miami Heart Institute; University of Miami School of Medicine.)
8. Volek JS, et al. Comparison of energy-restricted very low-carbohydrate and low-fat diets on weight loss and body composition in overweight men and women. Nutrition & Metabolism 2004, 1:13.  (Human Performance Laboratory, Department of Kinesiology, University of Connecticut)
9. Yancy WS Jr, et al. A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet To Treat Obesity and Hyperlipidemia. A Randomized, Controlled Trial. Ann Intern Med. 2004;140:769–777.  (Center for Health Services Research in Primary Care, Department of Veterans Affairs Medical Center; Duke University Medical Center)
10. Nichols-Richardsson SM, et al. Perceived Hunger Is Lower and Weight Loss Is Greater in Overweight Premenopausal Women Consuming a Low-Carbohydrate/High- Protein vs High-Carbohydrate/Low-Fat Diet. J Am Diet Assoc. 2005;105:1433–1437.  (Virginia Polytechinic Institute and State University)
11. Krebs NF, et al. Efficacy and Safety of a High Protein, Low Carbohydrate Diet for Weight Loss in Severely Obese Adolescents. J Pediatr 2010;157:252-8.  (University of Colorado, Denver)
12. Summer SS, et al. Adiponectin Changes in Relation to the Macronutrient Composition of a Weight-Loss Diet. Obesity (Silver Spring). 2011 Mar 31. 11; 2198–2204.  DOI: 10.1038/oby.2011.60  (Cincinnati Children's Hospital Medical Center; University of Cincinnati)
13. Dyson PA, et al. A low-carbohydrate diet is more effective in reducing body weight than healthy eating in both diabetic and non-diabetic subjects. Diabet Med. 2007 Dec;24(12):1430-5.  (Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, UK)
14. Keogh JB, et al. Effects of weight loss from a very-low-carbohydrate diet on endothelial function and markers of cardiovascular disease risk in subjects with abdominal obesity. Am J Clin Nutr 2008;87:567–76.  (The University of Adelaide, Adelaide, Australia)
15. Volek JS, et al. Carbohydrate Restriction has a More Favorable Impact on the Metabolic Syndrome than a Low Fat Diet. Lipids 2009;44:297–309.  (University of Connecticut)
16. Partsalaki I, et al. Metabolic impact of a ketogenic diet compared to a hypocaloric diet in obese children and adolescents. J Pediatr Endocrinol Metab. 2012;25(7-8):697-704.  (University of Patras School of Medicine, Patras, Achaea, Greece)
17. Daly ME, et al. Short-term effects of severe dietary carbohydrate-restriction advice in Type 2 diabetes–a randomized controlled trial. Diabet Med. 2006 Jan;23(1):15–20.  (Diabetes and Vascular Health Centre, Royal Devon and Exeter NHS Trust, Exeter, UK)
18. Westman EC, et al. The effect of a low-carbohydrate, ketogenic diet versus a low- glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutr. Metab (Lond.)2008 Dec 19;5:36.  (Duke University Medical Center)

 Note – Much of this list was sourced from www.dietdoctor.com/science.   Where necessary, the links were updated and the most recent, NIH funded study was added.  In addition, for each citation, the author’s affiliation is noted (in parentheses).