Learn Which Dietary Fats Can Actually Help You Lose Fat

It sounds contradictory, but consuming certain dietary fats can help you lose body fat. But you need to know what you're doing. Here's your guide.

Fats and cholesterol are the building blocks of key hormones such as thyroid hormone, oestrogen, testosterone, and cortisol. Under normal circumstances, when fat accounts for less than 15 percent of total calories, the production of those hormones begins to suffer. This has negative consequences for everything from fat burning and muscle growth to fertility and mood. Inadequate fat intake also impairs absorption of essential fat-soluble vitamins (A, D, E, and K), each of which has an important biological role.

On the flip side, getting more than 40 percent of total calories from fats can come at the expense of protein and fiber. Excessive intake of fats—which are the most calorie-dense nutrient at 9 calories per gram—can lead to unwanted weight gain, especially in people not accustomed to higher-fat diets.

The official recommendation from the American Dietetic Association is to get 20-35 percent of total calories from fat.[1] Based on my review of the literature, 0.3-0.5 grams of fat per pound of your goal body weight is adequate for optimizing hormone levels and meeting other physiological needs such as the absorption of fat-soluble vitamins, structure and funtion of cell membranes, blood clotting, wound healing, and brain and neuron function.

Dietary fat also helps suppress appetite by activating specific hormones in the gut and by slowing digestion.[2] Fats can also slow the release of nutrients from the small intestine, helping to promote stable blood sugar and a healthy glucose metabolism.

Choosing The Right Fats For Fat Loss

Certain types of fats are more beneficial for fat loss than others. A diet high in monounsaturated and polyunsaturated fatty acids, such as avocado, nuts, and fatty fish, has been shown to reduce insulin resistance. Insulin resistance is a dominant risk factor for type 2 diabetes and is often associated with obesity and high blood pressure.[3]

Omega-3 fatty acids are a type of polyunsaturated fat found in fatty fish, flaxseed, chia seeds, and walnuts. Omega-3's have been shown to enhance the health benefits associated with regular exercise, as well as reduce hunger cravings. Both can help you achieve your fat-loss goals![4,5]

Avoid trans fats, though. Found in processed foods containing partially hydrogenated oils, these fats are a significant risk factor for cardiovascular disease. Go easy on the saturated fat, too. Too much of it, along with inadequate intake of monounsaturated and omega-3 fats, can hinder fat loss. And it just might increase your risk of insulin resistance, obesity, and metabolic syndrome.[3] All can lead to type 2 diabetes.

While trans fats should be avoided completely, we do need a minimum amount of saturated fats for hormone regulation, cell messaging, and immune function. Certain saturated fats, like coconut oil, are rich in MCTs (medium-chain triglycerides) which can increase fat oxidation and may be beneficial for weight management. Other sources of saturated fats, like egg yolks and butter, are rich in essential fat-soluble vitamins, like A, D, E, and K.

Nevertheless, the current consensus among health authorities like the Harvard School of Health and the American Dietetic Association, based on reviews of all the available research, is that saturated fat should be limited to 10 percent or less of total calories.[1,6]

Still Fuzzy About Fats?

• Monounsaturated fats: olives and olive oil, canola oil, avocados and avocado oil, almonds, macadamias and most other nuts, sesame seeds, and pumpkin seeds
• Polyunsaturated fats (including omega-3): salmon, sardines, mackerel, herring, ground flaxseed and flaxseed oil, chia seeds, walnuts and walnut oil, and canola oil
• Saturated fats (limit to 10% total calories): coconuts and coconut oil, palm oil, butter and ghee, egg yolks, grass-fed red meats, free-range poultry, and full-fat dairy

The Bottom Line

Consuming all the "fat-loss foods" in the world will not reduce body fat unless you're eating fewer calories than you burn. You've probably heard it before, and the science still holds true: Calorie deficit is the chief requirement for fat loss.

Start by figuring out your total caloric requirements (factoring in exercise), reducing calories by 15-30 percent for fat loss, subtracting your protein and fat requirements, then using nutrient-dense carbohydrates to fill your remaining energy needs.

By Sarah Wilkins

References

1. Kris-Etherton, P. M., Innis, S., & Ammerican, D. A. (2007). Position of the American Dietetic Association and Dietitians of Canada: dietary fatty acids. Journal of the American Dietetic Association, 107(9), 1599-1611.
2. Little, T. J., Horowitz, M., & Feinle-Bisset, C. (2007). Modulation by high-fat diets of gastrointestinal function and hormones associated with the regulation of energy intake: implications for the pathophysiology of obesity. The American Journal of Clinical Nutrition, 86(3), 531-541.
3. Riccardi, G., Giacco, R., & Rivellese, A. A. (2004). Dietary fat, insulin sensitivity and the metabolic syndrome. Clinical Nutrition, 23(4), 447-456.
4. Parra, D., Ramel, A., Bandarra, N., Kiely, M., Martínez, J. A., & Thorsdottir, I. (2008). A diet rich in long chain omega-3 fatty acids modulates satiety in overweight and obese volunteers during weight loss. Appetite, 51(3), 676-680.
5. Hill, A. M., Buckley, J. D., Murphy, K. J., & Howe, P. R. (2007). Combining fish-oil supplements with regular aerobic exercise improves body composition and cardiovascular disease risk factors. The American Journal of Clinical Nutrition, 85(5), 1267-1274.
6. "The Truth about Fats: The Good, the Bad, and the In-between - Harvard Health." Harvard Health. N.p., 7 Aug. 2015. Web. 02 Aug. 2016.

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Why Aspartame May Prevent Weight Loss

Reaching for a diet soda may actually hinder weight loss efforts, a new study done in mice suggests.

In experiments, researchers found that the artificial sweetener aspartame, which is found in some diet drinks, may contribute to the development of a condition called "metabolic syndrome," which involves a cluster of symptoms, including high blood pressure, high cholesterol levels and a large waist size. People with metabolic syndrome face an increased risk of heart disease, stroke and diabetes.

The researchers found how aspartame could be linked with metabolic syndrome: Aspartame may stop a key gut enzyme from performing its work in breaking down fat during digestion. [7 Biggest Diet Myths]

"This is the novel mechanistic insight," and it may explain why diet drinks can be ineffective at helping people to lose weight, Dr. Richard Hodin, senior author of the study and a professor of surgery at Harvard Medical School, told Live Science.

The study included three separate experiments. In the first, researchers added the gut enzyme to solutions of diet soda and regular soda. They found that the activity of the enzyme was significantly lower in the solutions of diet soda as compared to the solutions of regular soda.

Normally, the enzyme — intestinal alkaline phosphatase, or IAP — works in the intestines to break down cholesterol and fatty acids. Previous studies by the researchers showed that levels of IAP may be linked with people's risk of obesity, diabetes and metabolic syndrome.

In the second experiment, researchers looked at the effects of aspartame in the small intestines of male mice. They injected either a solution containing aspartame or a placebo solution of salt water into the small intestines of the mice, and then measured the same gut enzyme's activity. They found that 3 hours later, the enzyme's activity was 50 percent lower in mice that were injected with the aspartame solution as compared to the mice injected with the salt water.

In the final experiment, the researchers looked at four groups of male mice over a period of 18 weeks: The mice were all allowed to eat as much food as they wanted, but two groups were given normal food and two groups were given high-fat food. Within each division, one group received water to drink that contained aspartame, while the other received regular water to drink. [5 Experts Answer: Is Diet Soda Bad for You?]

At the end of this experiment, the researchers found that the mice given the high-fat food and the aspartame-infused water gained more weight than the mice fed a high-fat food and the regular water.

However, the aspartame did not seem to make a difference for the mice on the normal diet: There was no difference in weight gain between the group given aspartame water and the group given regular water.

In addition to the difference in weight gain among the mice on the high-fat diet, the researchers also found that the mice on both diets that drank the aspartame-infused water had significantly higher levels of glucose intolerance than mice that drank the regular water. Glucose intolerance is a condition in which the body has trouble using the glucose in the bloodstream, leading to higher levels of glucose in the blood, and which may lead to diabetes.

Also, both of the groups of mice that drank the aspartame-infused water showed increased markers of inflammation, which previously has been linked to the development of the metabolic syndrome, the researchers said.

The new results should be confirmed in experiments with a larger sample size, the researchers said. In addition, only male mice were used in the experiment, which is significant because male and female mice tend to react differently to dietary changes; for example, male mice tend to have higher levels of diet-induced inflammation, and female mice have better insulin sensitivity.

It remains unclear whether the findings may apply to people.

The effects of aspartame may be more complicated in humans, due to a "number of factors related to human behavior," Hodin told Live Science. However, he said, all else being equal, "diet drinks are probably not a great alternative to sugary sodas. Water is probably better."

Original on Live Science. 

By Stephanie Bucklin, Live Science Contributor

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