Cold showers is changing our relationship with cold, similarly fasting is changing our relationship with  hunger. 

To be healthy mentally ( during winter) need to accept the cold, to be healthy physically need to accept hunger. 

Both are same stop seeking comfort in food and warmth. that sounds brutal, but it is coming back to the same thing, show gratitude for everything good and bad. accept all sensations, food hunger, warm and cold, hot and cool. Equanimity. becoming Stitha Pragnya . 

I m thinking only way to stop struggling with weight is getting this relationship with hunger and food right