Olive oil, derived from the fruit of the olive tree, is a staple in the Mediterranean diet and has long been celebrated for its various health benefits. These benefits range from improved heart health and reduced risk of certain cancers to enhanced nutrient absorption and better gut health. However, the question remains: can olive oil contribute to weight loss? This article examines the evidence, separating anecdotal claims from scientific findings to provide a comprehensive understanding of olive oil's role in weight management.
The Health Benefits of Olive Oil
Olive oil offers a multitude of health advantages. Including olive oil in the diet has been linked to improved heart health and reduced risk of certain types of cancers, as well as promoting satiety and overall digestive health. A study analyzing data from 22,000 Italian men and women concluded that higher olive oil consumption was tied to lower rates of cancer, heart disease, and mortality, regardless of overall diet quality. Moreover, eating a Mediterranean diet, which includes olive oil in moderation, may lower the risk of breast cancer by 13 percent, according to a meta-analysis of 31 studies. Consuming olive oil (1.5 to 2 teaspoons daily) was associated with a 28 percent lower risk of dementia-related death, according to another study.
Olive oil also aids in nutrient absorption. Olive oil helps the body absorb fat-soluble vitamins (like vitamins A, D, E, and K) from other foods. When you add olive oil to your salad, for example, you’re helping your body absorb these fat-soluble vitamins more efficiently.
Furthermore, olive oil can contribute to a healthy gut. Consuming 3 to 4 tablespoons of extra-virgin olive oil daily may stimulate the growth of beneficial microorganisms in the gut microbiome.
Olive Oil and Fat Loss: Clinical Evidence
Despite the widespread use of extra virgin olive oil (EVOO) in obese individuals to treat cardiovascular diseases, the role of EVOO on weight/fat reduction remained unclear until more recent studies.
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One randomized, double-blinded, placebo-controlled clinical trial involved 41 adult women with excess body fat (mean ± SD 27.0 ± 0.9 year old, 46.8 ± 0.6% of total body fat). These women received daily high-fat breakfasts containing 25 mL of soybean oil (control group, n = 20) or EVOO (EVOO group, n = 21) during nine consecutive weeks. Breakfasts were part of an energy-restricted normal-fat diets (-2090 kJ, ~32%E from fat). The results indicated that fat loss was approximately 80% higher in the EVOO group compared to the control group (mean ± SE: -2.4 ± 0.3 kg vs. -1.3 ± 0.4 kg, P = 0.037). Additionally, EVOO consumption reduced diastolic blood pressure when compared to the control group (-5.1 ± 1.6 mmHg vs. +0.3 ± 1.2 mmHg, P = 0.011).
Another study compared the effects of consuming medium-chain triacylglycerols (MCTs) versus long-chain triacylglycerols, such as those found in olive oil, as part of a weight-loss program. Forty-nine overweight men and women, aged 19-50 years, consumed either 18-24 g/d of MCT oil or olive oil as part of a weight-loss program for 16 weeks. All subjects received weekly group weight-loss counseling. The study found that MCT oil consumption resulted in lower endpoint body weight than did olive oil (−1.67 ± 0.67 kg). There was also a trend toward greater loss of fat mass with MCT consumption than with olive oil.
MCTs vs. LCTs: Understanding the Difference
Dietary fat is often blamed for the rising prevalence of obesity. However, all fats are not equal in their metabolic effects. Medium-chain triacylglycerols (MCTs), which typically contain fatty acids with chain lengths of ≤10 carbon atoms, are processed differently from long-chain triacylglycerols (LCTs) by the body. Medium-chain fatty acids can be absorbed in the gastrointestinal tract and transported to the liver via the portal circulation without incorporation into chylomicrons. As a result, MCTs are oxidized to a greater extent than are LCTs and have less opportunity for deposition into adipose tissue.
Human studies have also shown that MCTs increase fat oxidation and thermogenesis compared with LCTs in short-term feeding studies. MCT oil may be a useful adjunct to a weight-loss diet. Some data also suggest that MCTs increase satiety when compared with LCTs.
The Study Design and Results
Subjects were recruited from the Birmingham, AL, greater metropolitan area through newspaper advertisements and flyers. Both men and women, aged 19 to 50 y, with a body mass index (in kg/m2) of 27-33 were recruited. For inclusion in the study, all participants were required to be weight stable for ≥6 mo and to be free of chronic diseases.
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Once the subjects were enrolled in the study, they were randomly assigned to either MCT oil or olive oil consumption. MCT oil contained octanoate and decanoate only (100% saturated medium-chain fatty acids). Olive oil was a blend of ≈14% saturated fatty acids, 72% monounsaturated fatty acids, and 14% polyunsaturated fatty acids. All fatty acids in olive oil were long-chain fatty acids.
The subjects were provided EatRight materials weekly and discussed the weight-loss principles taught with the dietitian. Body weight and waist circumference were measured at each weekly session by the clinical coordinator (AB). As part of the weight-loss program, the subjects were counseled to reduce their caloric intakes to 1500 kcal/d for women and 1800 kcal/d for men. Therefore, all subjects received ≈12% of their prescribed weight-loss energy requirements in the form of the study oil (18 g for women and 24 g for men).
Body weight was measured to the nearest 0.5 kg with a standard beam scale. Height was measured to the nearest 0.1 cm with a stadiometer. Subjects underwent a full-body DXA scan at baseline and at 16 weeks. CT scans were performed to assess changes in intraabdominal adipose tissue and subcutaneous abdominal adipose tissue with weight loss.
A total of 49 subjects were enrolled in the study and 31 completed the study (MCT, n = 16; olive oil, n = 15). There was a significant effect of week and a trend for a diet-by-week interaction on body weight. Body weight at the study endpoint was lower in the MCT group than in the olive oil group.
There was no significant effect of diet and no diet-by-week interaction on waist circumference in either the completers or the last observation carried forward analysis. There was a trend toward a diet-by-week interaction on absolute fat mass. Endpoint absolute fat mass was lower in the MCT group than in the olive oil group.
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Data from CT analyses showed a trend toward an effect of week, an effect of diet, and a diet-by-week interaction on muscle area. Muscle area was significantly greater at the study endpoint with olive oil than with MCT oil consumption.
The inclusion of MCT oil in a weight-loss program leads to greater weight loss than does the inclusion of a similar amount of olive oil. In this study, subjects consuming MCT as part of their weight-loss diet lost an average of 1.7 kg more than did subjects consuming olive oil as part of their weight-loss diet.
Olive Oil in the Mediterranean Diet
Many of olive oil’s benefits have been observed in the context of following a Mediterranean diet. This eating pattern is characterized by a high consumption of fruits, vegetables, whole grains, potatoes, legumes, nuts, and seeds. While the diet often incorporates fish, the main fat source is olive oil, and it also limits red meat and sweets.
Olive oil contains monounsaturated fatty acids (MUFAs), which have one unsaturated carbon bond in their chemical composition and are typically liquid at room temperature. One older 4-week study found men with overweight or obesity who replaced saturated fat with monounsaturated fats in their diets experienced small but significant weight loss, compared with a saturated-fat-rich diet, despite no major change in total fat or calorie intake. More recent research agrees that unsaturated fatty acids are likely more beneficial than saturated fats when it comes to healthy weight maintenance. Diets rich in monounsaturated fats have also been shown to prevent weight gain and the accumulation of fat in animal studies.
Olive Oil and Thermogenesis
Olive oil can help your body burn calories and manage weight by enhancing thermogenesis - the process of heat production that burns fat. Research highlights olive oil's role in boosting metabolism. The advantages go beyond short-term effects. Consuming 2-4 tablespoons of high-quality olive oil daily has been shown to support these metabolic benefits. Olive oil, rich in monounsaturated fats (MUFAs) and phenolic compounds like hydroxytyrosol, plays an important role in boosting thermogenesis and aiding weight management.
Cold-pressed oils made shortly after harvest are especially effective, as they preserve the highest levels of these important compounds.
Practical Ways to Incorporate Olive Oil into Your Diet
For the best results, aim for 2-4 tablespoons of olive oil daily. Here are a few ideas:
- Mediterranean Power Bowl: Combine roasted veggies, quinoa, and fresh herbs, then toss with 1 tablespoon of olive oil.
- Metabolic-Boost Marinade: Blend 2 tablespoons of olive oil with lemon juice and herbs.
- Thermogenic Dressing: Whisk together 1 tablespoon of olive oil, balsamic vinegar, and fresh garlic.
Olive Oil: Timing and Quantity
If you want to lose weight and improve your digestion, taking it on an empty stomach or before meals can be ideal. If you are looking to relax and promote recovery, taking it before bed is a great option. Ideally, you should consume between 1 and 3 tablespoons per day.
Taking a tablespoon of EVOO about 20-30 minutes before eating can work wonders: You will feel more satiated, which will help you eat less naturally. EVOO before bed can help you improve nighttime digestion and prevent inflammation and promote the correct absorption of essential nutrients.
Olive Oil and Balsamic Vinegar
Extra virgin olive oil and balsamic vinegar make an unbeatable duo. Balsamic vinegar contains acetic acid, which stimulates fat burning and improves digestion. The ideal is to use 1 tablespoon of EVOO and 1 teaspoon of balsamic vinegar in your meals.
- Roasted Vegetables: Cut the vegetables into slices, mix them with EVOO and balsamic vinegar, and roast them in the oven at 200ºC for 20 minutes.
- Gourmet Marinade: Mix everything together and spread it on grilled chicken or salmon before cooking. You'll be surprised by the depth of flavor it adds.
Caveats and Considerations
While olive oil can be beneficial for weight loss when consumed in limited quantities, steer clear of claims that olive oil massages and detoxes are a long-term solution. There are 119 calories and 13.5 grams of fat in 1 tablespoon (15 mL) of olive oil. This can quickly add up on a calorie-restricted diet, so it’s best to incorporate olive oil in limited quantities as not to promote weight gain.
One systematic review of 11 randomized controlled studies found that following an olive-oil-enriched diet for at least 12 weeks reduced weight more than following a control diet.