**8. Anti-obesity effects of flaxseed**

Obesity is a serious health issue and a significant contributor to the risk of diabetes, heart disease, and cancer. By 2030, it is anticipated that 1.12 billion people worldwide would be obese [58]. Type 2 diabetes, hypertension, inflammation, metabolic syndrome, cardiovascular dysfunction, and non-alcoholic fatty liver disease are among the comorbid conditions that the majority of obese persons have [59]. Also, it has been reported in several studies that obesity is an important risk factor for some type of cancers [60]. As a result, preventing obesity is essential for lowering chronic disease rates. Several studies have evaluated the effect of flaxseed supplementation in obese people.

Mohammadi-Sartang in a meta-analysis from 45 randomized controlled trial studies and 2789 participants showed that flaxseed consumption led to a significant reduction in body weight, body mass index, and waist circumference. Also, they found that the flaxseed supplementation caused significant weight loss if flaxseed was taken with a dose higher than 30 grams per day, and the duration of the intervention was more than 12 weeks [61]. Several mechanisms have been proposed for the anti-obesity effects of flaxseed. As mentioned, flaxseed is one of the richest sources of lignan (primarily SDG), and its lignan content is up to 100 times higher than that of some other plants [62, 63]. SDG, a type of purified lignans, has been demonstrated to decrease visceral (abdominal) fat in mice when compared with animals that did not consume SDG [64]. The researchers proposed that a drop in the mRNA levels of sterol regulatory element-binding proteins, which are essential for the synthesis of triacylglycerol, may result from flaxseed's high amount of SDG [64]. Also, the results of some studies have shown that the lignans in flaxseed regulate the expression of adiponectin and stimulate fat oxidation, all of which prevent excessive fat accumulation and obesity [64, 65]. It has been demonstrated that dietary fiber, especially soluble fiber, has anti-obesity properties that reduce body weight. By delaying gastric emptying, causing sensations of fullness via absorbing significant amounts of water, and/or increasing the levels of short chain fatty acids, which operate to induce satiety by a wide range of mechanisms, dietary fiber can help control weight or aid weight loss [66].
