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Overcoming midlife weight gain

There is supportive scientific evidence that intermittent fasting, including 5:2 diets and restricted time feeding, can be sustainable ways for women to manage weight gain.

In recent years, the world of nutrition and weight loss has been captivated by the idea of intermittent fasting (IF) and restricted time feeding (RTF) diets. Among these, the 5:2 diet has garnered significant attention. These dietary approaches have become particularly popular among women seeking to shed excess pounds and improve their overall health. In this blog post, we will explore the science behind these methods, drawing on the protein leverage hypothesis, glucose-insulin dynamics, and calorie excess theories of weight gain and loss.

Understanding Intermittent Fasting and Restricted Time Feeding

Intermittent fasting involves alternating periods of eating and fasting in order to reduce calorie intake. There are various approaches, such as the 5:2 diet (where calories are limited to under 500-600 a day for 2 days of the week), or the Eat-Stop-Eat method (24-hour fasts once or twice a week). On the other hand, restricted time feeding limits daily food consumption to a specific time window, often around 8-10 hours, (eg 16/8 method -16 hours fasting, 8 hours eating) and does not necessarily dictate any calorie restriction.

The reason these diets can work is dual – they generally result in overall calorie (or energy) deficit and they can be sustained over time. They have less impact on quality of life than other diets and can fit easily into existing lifestyles.

Calorie restriction has gone out of favour lately and “keto” has crept in, so  let’s take a look at the current theories behind weight management so we can better identify why different food strategies will work better for different individuals.


1. Calorie Excess Theory

The calorie excess theory is a fundamental concept in weight management. When we consume more calories than our body needs for daily energy expenditure, the excess calories are stored for later as fat, leading to weight gain. In today’s world of food abundance, energy stores are rarely ever required. IF and RTF can promote weight loss by reducing the overall window in which food is consumed, potentially leading to a natural and sustainable reduction in overall calorie intake.


2. Glucose-Insulin Dynamics

The glucose-insulin dynamics theory explains how our body responds to different types of food. Carbohydrates, particularly refined sugars and high-glycemic foods, can lead to rapid spikes in blood glucose levels. In response, the pancreas releases insulin to regulate blood sugar. Insulin promotes fat storage, and when these cycles occur frequently, it can contribute to weight gain and even the development of insulin resistance and type 2 diabetes.

IF and RTF can help stabilise blood glucose levels. During fasting periods, insulin levels drop, allowing the body to access its own stored fat for energy. This metabolic shift may facilitate weight loss, especially when combined with a diet that emphasises complex carbohydrates, fiber-rich foods, and healthy fats while reducing simple sugars.

Low carbohydrate and ketogenic diets (where dietary carbs are so low the body’s ketones rise) both focus on this theory. ‘Keto’ diets often don’t work as well for women as they do for men. In addition, many carbohydrate containing foods are high in fibre and other nutrients. Keto diets that contain high saturated or animal fats may also raise unhealthy blood lipid levels in some people.


3. Protein Leverage Hypothesis

The protein leverage hypothesis posits that our body regulates its food intake based on the proportion of protein in our diet. When protein intake is low, the body may seek to consume more food overall to meet its protein needs, leading to overeating and potential weight gain. By prioritising protein-rich foods during intermittent fasting and restricted time feeding, individuals may also experience increased satiety and consume fewer overall calories. For women aiming to lose weight, focusing on adequate protein intake across the eating window can ensure adequate protein intake and play a role in preventing overeating during non-fasting hours.


Benefits and Considerations for Women

IF and RTF may offer several benefits for women striving for weight loss:

  1. Improved Metabolic Health: These dietary approaches have been shown to enhance insulin sensitivity and metabolic flexibility, which may be particularly beneficial for women dealing with insulin resistance and weight gain around menopause.
  2. Hormonal Balance: Some studies suggest that intermittent fasting could positively impact hormones like leptin and ghrelin, which play a role in appetite regulation.
  3. Sustainable Lifestyle: IF and RTF can be more sustainable for some individuals, as they allow for flexibility and do not necessitate strict calorie counting or constant meal planning.

It’s always essential to consider individual differences, personal preferences, lifestyle and potential health conditions. Women who have a history of disordered eating should consult with a healthcare professional before adopting these diets.

Intermittent fasting and restricted time feeding have gained popularity among women seeking effective weight loss strategies. The underlying science, including the protein leverage hypothesis, glucose-insulin dynamics, and calorie excess theories, supports the potential effectiveness of these dietary approaches. By embracing a balanced and protein-rich diet during eating periods and ensuring nutrient-dense food choices, women can harness the power of intermittent fasting and restricted time feeding to achieve their weight loss goals while promoting overall health and wellness. Remember, it’s essential to listen to your body and consult with a healthcare professional before making significant changes to your eating habits.

This information is for general educational purposes only and does not constitute medical advice. Please see your health professional for advice that is personalised to you.
Key Take Aways

The theories behind weight management include calorie restriction, glucose-insulin balance and protein leverage.

Intermittent fasting and time restricted eating are both sustainable ways for midlife women to manage weight.

Studies suggest that IMF and RTF strategies are safe and tolerable and produce 3–8% weight loss in adults with overweight or obesity.


Other resources

Effectiveness of Intermittent Fasting and Time-Restricted Feeding Compared to Continuous Energy Restriction for Weight Loss. Rynders et al. Nutrients 2009