Can Eating Nuts Help You Lose Weight?
You probably know that nuts are high in fat. Because they are very energy-dense (containing a large number of calories compared to volume), it is natural to assume that eating nuts will contribute to weight gain. However, a number of recent scientific studies conducted on the effect of nut consumption on body weight provide evidence contrary to this assumption.
An examination of the literature on this topic, conducted by Richard Mattes and colleagues and published in The Journal of Nutrition, actually found that eating nuts is not associated with a higher body weight – in fact, many studies found that people who eat nuts have a lower Body Mass Index (BMI) than people who don't eat nuts.
Nuts Found Not To Cause Weight Gain
Several clinical trials have found that nut consumption has a limited impact on body weight. In one trial, healthy adults were provided with an amount of almonds equivalent to 15% of their calculated energy needs each day. It was predicted that this addition of daily calories would result in a weight gain of 6.4 kg, but the actual weight gain was only 0.65 kg for men and 0.14 kg for women – about 10% or less than the expected amount.
Another recent trial, in which healthy but overweight women were instructed to eat a portion of almonds daily for 10 weeks, found no change in weight at the end of the 10 week period, despite a predicted weight gain of 3.4 kg.
Nuts Can Aid Weight Loss
A number of clinical studies have found that the addition of nuts to a diet meant for weight loss not only doesn't reduce the effectiveness of the diet, but can actually improve both quality of diet and amount of weight loss. A comparison of almonds and complex carbohydrates found that people consuming almonds lost more weight and saw a greater reduction in BMI, waist circumference, and fat mass.
A second study found that a diet containing moderate amounts of fat from nuts – defined as 35% of energy from fat – resulted in greater weight loss than a diet low in fat, where 20% of energy came from fat. Study participants who were on the moderate-fat diet were also more likely to stick with the diet than those on the low-fat diet.
Why Might Nuts Help You Lose Weight?
- Nuts help you feel less hungry. Questionnaires have found that the consumption of nuts results in a significant reduction in levels of hunger reported by respondents, although the reason for this is unknown.
- You eat fewer calories at other times. For an unknown reason, it appears eating nuts results in a lower calorie consumption at later meals. The majority of calories obtained by eating nuts – an estimated 65-75% – are offset by this reduced intake of other foods.
- Energy from whole nuts is not readily absorbed by your body. Studies have consistently found that a large amount of fat from nuts passes through the digestive tract without being absorbed. An estimated 10-20% of a nut's calories are thought to be lost due to this limited efficiency of energy absorption. The cell walls of nuts are resistant to gastrointestinal enzymes, meaning that any cells not broken by chewing may not release the fat that they store.
- Nuts may help you burn more calories. Eating nuts has been found to increase the amount of energy you expend while resting. One trial found that consuming peanuts increased resting energy expenditure (REE) by 11%. What exactly does this mean? As an example, the REE of a woman who is 30 years old, 5 feet and 4 inches tall, and 160 pounds is 1511 calories per day. Replacing some of her diet with nuts could help her burn 11% more calories while at rest, or an extra 166 calories per day. This translates to 17lb of weight loss in a year!
Even though nuts are high in fat, scientific studies are showing that a diet containing nuts can be helpful in losing weight and in maintaining a healthy body weight. Not only do nuts make you feel fuller and want to eat less, the fat they contain is not readily absorbed by your body and they may even help you burn more calories while at rest. These advantages suggest that adding a moderate amount of nuts to your diet is a healthy move.
About the Author
Matthew Contantine is a biologist and postdoctoral fellow at Washington University School of Medicine. He has a variety of research interests and reviews popular meal replacement diets on his weight loss blog.